Found a small bug in tile editing mode:
Enter Tile Edit mode -> START -> B -> some times the location cursor sprites are no longer visible.
I think they are still getting moved in the OAM, but their tile is set to one which is all clear. Mainly happens for the first 3.
Edit: The tile select mode copy/paste instructions look like they might be reversed? START seems to paste and SELECT seems to copy.
And, a lil drawing:
