Lockframe will not lock the frame you are looking at
Most of the time it will lock the frames below or above if there are multiple for example in a mapart. I spent 10 minutes trying to lock 12 frames and only managed to do every second layer of item frames even if I pillared up, stood at different distances and aimed at different places.
-1383 69 -18083 coords if you want to try to lock the item frames