This has been a problem for me since November, but I did not pursue it before becasue I was not sure where to report it.
In East Anglia, there is an artifact at a temple that is south of the Serpent's Landing location. The artifact was collected but the icon remains on the map and it was not registered as collected, therefore preventing me from completing all the artifacts for the region as well as preventing trophy acquisiton for trophies related to roman masks and artifacts. No patch as fixed anything yet, and honestly, I don't expect it to be fixed. If I noticed it at the time a reloaded save might have fixed it but that is no longer an option, nor will I start an entire new playthrough where I am not done of my first one that is now over 120 hours.
I do not know what else to do other than post this here in the non-existan hopes it gets reported or noticed in some manner.