In response to on AnswerHub:
So this has happened to me 3 times in 3 slightly different manners (the first time was what I linked above).
I’ll try to describe in more detail what it’s like:
I’m working, and at some point I suddenly realize my character isn’t properly set up anymore. This only happens to my blueprint characters that are derived from another blueprint character.
The first time it happened there was no indication that in the editor it was broken. After several days of not playing the packaged game, when I finally did play it, the mesh was gone, and the rotation on the character (not camera) was broken. So I have no idea what led to that happening, but I posted my story in the link above.
The second time it occurred my issue was apparent in the editor (whereas before only the packaged game was showing up broken). I had been working with the parent class a bunch, and kept switching to the derived classes. I was just tweaking CharacterMovement variables. At some point I noticed the mesh was missing in one of my derived classes. The character mesh was None, and there’s no way to ‘reset’ to default. I fixed it by rebuilding the blueprint (so I right clicked on the parent BP and pressed “Create Blueprint based on This”). I copied the nodes over from the old blueprint and then replaced references (this is also broken though because it can’t seem to properly replace casts, so I had to manually replace those). The new blueprint worked (well, the same as the old, nothing was logically different).
The third time it occurred, yesterday, I was working with animations and sounds. I added an animation montage to the mesh my parent BP gives to its children, and then had only one of the child BPs use it. It was working fine, and then I moved onto sound. I then played a bit with the child BPs camera behavior (which I override from the parent BP) and after that I suddenly realized the child BP was missing his mesh. I reset the mesh, saved, and that worked in editor, but when I packaged the game he was missing. I tried reparenting the childBP and saving, but that didn’t fix it. So then I tried rebuilding the child blueprint (extremely annoying) just as I did with the second occurrence, and that did not fix it this time. I’m not even that certain editing the camera was the last thing I did. I just mentioned it because I was setting the Mesh to invisible for this particular character when they started, since they’re meant to be played from the first person perspective.
I think the issue has something to do with derived blueprints.