We were following this “Option 2”
Using queued tracking.
However, during the upgrade from 3 to 4, the QueuedTracking plugin was disabled because it’s no longer compatible with 4.
We will instead need to pull this gap data in from the server logs.
I think the FAQ should be updated to include that warning, since QueuedTracking is not reliable for large instances during Matomo upgrades which in turn force an upgrade to QueuedTracking.