I have a map that has icons on it (placed via commands, if that matters). I keep it in a frame. Sometimes when I re-enter the room with that frame, those icons are missing. I fix this by hitting the map to destroy the frame, putting in a new frame, and then putting the map back into the frame. (Well, technically a new copy of the same map, of which I keep a stack in a chest.)
It is hard to reproduce this bug, but it has persisted since at least 1.20, probably farther (I don’t keep records that far back). And it isn’t rare. It’s just that I cannot figure out what triggers it. It may happen as often as every 10 hours of gameplay, but it’s hard to be sure because I can only notice it when I enter the room and see the map, which I do only sometimes.
Without proper steps to reproduce, it is very difficult or even impossible to confirm the issue you are describing.
I will be resolving this issue as “Cannot Reproduce” because of this, but please let me know in a comment if you are able to find a way to consistently have this issue occur.