Overview
You'll understand why Facebook (Meta) doesn't always attribute events to specific campaigns, how attribution windows work, and what causes discrepancies between Events Manager and Ads Manager reporting.
Understanding Facebook Attribution
Facebook uses attribution windows to determine which campaigns receive credit for conversions. An attribution window is the timeframe between when someone interacts with your ad (by clicking or viewing it) and when they complete a conversion action.
When an event doesn't appear attributed to your campaign, it's usually because the conversion happened outside the attribution window or there's no clear link between the ad interaction and the conversion.
How Attribution Windows Work
Meta currently supports these attribution windows:
Click-Through Attribution
1-day click — Conversions must happen within 24 hours of clicking your ad
7-day click — Conversions must happen within 7 days of clicking your ad (default setting)
View-Through Attribution
1-day view — Conversions must happen within 24 hours of viewing your ad (without clicking)
Engaged-View Attribution
1-day engaged view — Conversions must happen within 1 day after watching at least 10 seconds of a video ad
The standard Meta reporting window is 7-day click / 1-day view. This means a conversion that happens up to 7 days after someone clicked an ad (or 1 day after viewing it) can be credited to that campaign.
Why Events Show in Events Manager but Not in Ads Manager
This is one of the most common attribution issues. Here's why it happens:
1. No Attribution to Ads
Events Manager displays all events tracked by your Pixel and Conversions API, regardless of their source. Ads Manager only shows events that are linked to ad interactions within your attribution window.
If someone converts through organic traffic, direct visits, or email campaigns, the event appears in Events Manager but won't be attributed to any ad campaign.
2. Events Occurred Outside the Attribution Window
If a user clicked your ad 8 days ago and converted today, the conversion won't be attributed to your campaign (assuming you're using the default 7-day click window).
Many advertisers see lower conversion numbers in Ads Manager compared to Events Manager because not all conversions can be attributed to paid ads. This doesn't mean your tracking is broken—it means some conversions came from other sources.
3. Wrong Optimization Event Selected
If your campaign is optimized for Purchases but you're looking for Add to Cart events in Ads Manager, those metrics may not appear unless you manually select them in your reporting columns.
4. Event Deduplication Issues
When running both Pixel (browser-side) and CAPI (server-side) tracking, Facebook uses event IDs to deduplicate events. If event IDs don't match properly, events may not be attributed correctly to campaigns.
PixelFlow automatically handles event deduplication by sharing the same event ID between Pixel and CAPI events. This ensures accurate attribution and prevents double-counting.
Why Conversions Appear Days Later
You might notice conversion numbers changing days after a campaign runs. This is normal and happens because:
Meta Attributes Conversions by When the Ad Was Clicked, Not When the Conversion Happened
If someone clicks your ad on Monday but converts on Friday, that conversion is attributed back to Monday's campaign performance. This means yesterday's conversion numbers can still increase as late conversions come in.
For example, if you review Monday's performance on Tuesday, you might see 50 conversions. But when you check again on Friday, Monday now shows 65 conversions because some users took longer to convert after clicking the ad on Monday.
Reporting Delays for iOS 14+ Users
Due to Apple's App Tracking Transparency (ATT) policy, Facebook can only receive the highest-ranking event from iOS users who opt out of tracking. This data can take up to 72 hours to process, causing delayed reporting.
To get more accurate same-day reporting, adjust your reporting window in Ads Manager to end 3-4 days prior to today. This accounts for iOS reporting delays.
Common Scenarios and What They Mean
Scenario 1: Events Manager Shows More Conversions
What's happening: You're tracking all conversions (organic, paid, direct), but Ads Manager only shows paid attribution.
Action: This is expected behavior. Use Events Manager for overall conversion tracking and Ads Manager specifically for ad-attributed performance.
Scenario 2: Conversions Appear in Wrong Campaign
What's happening: Facebook attributes conversions to the last ad click within the attribution window. If someone clicked multiple ads, the most recent one gets credit.
Action: Review your attribution model settings. Consider using first-click or linear attribution for better visibility into the full customer journey.
Scenario 3: No Conversions Show Despite Sending Events
What's happening: Events are being sent successfully, but there's no link between the ad click and the conversion.
Action: Verify that your tracking includes the fbp (Facebook browser pixel) and fbc (Facebook click) parameters. These cookies link users to their ad interactions.
PixelFlow automatically captures and includes both fbp and fbc parameters in all events sent to Meta, ensuring proper attribution. You can view these parameters in your Events Log in the PixelFlow dashboard.
How to Align Your Numbers
If you want your Meta numbers to align more closely with actual events sent:
Use a 1-day click attribution window — This limits Meta's credit to conversions within 24 hours of an ad click, reducing delayed attributions
Check the same time period — Make sure you're comparing the same date ranges in Events Manager and Ads Manager
Review by attribution — Remember that Ads Manager shows conversions by attribution date (when the ad was clicked), not conversion date (when the action happened)
Monitor both windows — Many advertisers track both 1-day and 7-day click windows side-by-side for a complete picture
Switching to a shorter attribution window (like 1-day click) will show fewer attributed conversions in your reports. This doesn't mean your ads are performing worse—it just means you're using a stricter measurement model.
Verification Steps
To ensure your attribution is working correctly:
Check your Pixel installation — Use the Facebook Pixel Helper to verify your Pixel is firing on all pages
Verify fbclid parameter — When users click your ads, they should have
?fbclid=in the URL. This links the visit to the ad clickReview event payloads — In PixelFlow's Events Log, check that events include both
fbpandfbcparametersConfirm attribution settings — In Ads Manager, click into an ad set and verify the attribution window under Cost per Result Goal → Show More Options → Attribution Settings
Limitations
Attribution windows were shortened from 28 days to 7 days after iOS 14 privacy changes
View-through attribution is limited to 1 day (previously 7 days was available)
iOS users who opt out of tracking have delayed reporting (up to 72 hours)
Facebook cannot track conversions that happen in different browsers or devices unless the user is logged into Facebook
Conversions older than your attribution window will never be attributed to campaigns
What's Next
Now that you understand attribution windows and why events may not show in specific campaigns, you might want to:
Learn how to test and verify your PixelFlow CAPI setup
Understand how to improve event match quality scores
Review required Meta event parameters for proper tracking
Getting Help
If you're still experiencing attribution issues after reviewing this guide, check:
Your Events Log in PixelFlow to verify events are being sent with
fbpandfbcparametersMeta Events Manager diagnostics for any tracking warnings or errors
That your Pixel is installed on all pages of your website, not just conversion pages
If the issue persists, contact PixelFlow support with your event details, including the event ID and timestamp, so we can investigate the payload sent to Meta.