I often make multiple copies of a text layer and only change the font so I can decide which font I want to go with, but when I go to make changes (move, resize, etc.) to one of these layers they all disappear except for the original and the active layer. Then I have to undo (which restores the missing layers) and try again and hope that they don't all disappear. Usually after one or two rounds of disappearances it settles down. This has been going on for several years at least.