Event Deduplication stoped working (or reporting)

I use the the shopify facebook app for pixel tracking and capi purchase events.

When looking at the purchase event in the Events Manager app it used to show how many of the server side events were deduplicated and how many were processed.

Now its always reporting 0 for deduplicated events. Its odd because past dates that were showing x deduplicated events are now all reporting 0. I have a screenshot to compare so I am certain that they were previously deduplicated.

Any ideea why this would happen?

Asked about 2 months ago