Another data point is I had the filter show upgrade space available within clearance window for a booking yesterday. Booked it, and all but one leg upgraded. Checked back with the eup filter and it still says space on that one leg is available, checked expert flyer and indeed R=0.
Sent a quick note to concierge to see if I can take a different routing, unfortunately no R space available on any other routings.

They did confirm that AC IT is still working on the issue with the eup filter.

The good news is I woke up to an upgrade clearing on the one leg in question.

Another data point was I was looking for available eups from YVR to PVG last night later in the year, October-ish and it would not show available eups. Haven't checked expert flyer yet.