No, i haven't. It must be exceedingly rare. (And yes I've been up there and tried getting out of the loaded chunk and quickly back in - if something like chunks exists in this game - saving and loading the game, opening the near chest under the waterfall. But it didn't happen again)
If I were you, I'd just put that bug in a box with all the screenshots provided and stop looking at it until someone else stubles apon it again and provides more information. (In a github project I'd create an 'issue', but something like that doesn't exist here, does it?)
Right now performance (with saving video settings) and controls (with adjustable keybinds) should be priority.
Once you have those two you might be able to get more players and therefore more testers that don't give up on it after the first few seconds because of those two and maybe then someone else stubles apon more info about that tiny, item texture, loading issue.
But as I don't know much about unreal engine or the current state of your codebase, that is just my opinion.