Not the same problem, but tangentially related, is this StreetComplete issue about SC users not seeing that they have been blocked from the API (usually until they do something, such as read a message).
This issue about PM notifications is fixed, so it doesn’t make sense to morph it into a different discussion about API blocks, but I thought that it did make sense to mention the other issue too since it is somewhat related - in both cases SC controls all the UI and OSM is “just an API” that it calls.