The addon does not recognize that I already learned the Illusion "Mark of the Bleeding Hollow" and therefore does not complete the LFR collection

Screenshot

@BarbokOL Are you still seeing an issue here? Did you try shift clicking on anything in ATT to trigger a refresh? I checked my Mark of the Bleeding Hollow and it's working fine.

It may also be worth speaking with a transmogrifier, opening the illusions, hovering on the Mark of the Bleeding Hollow, and then triggering a refresh.

No other reports of any issues with this. Illusions sometimes need to be forcibly refreshed to be marked as collected (Shift + Click in ATT list).