ALL alt answers for 2 course sections completely wiped

So somehow, suddenly and without any explanation, an entire 2 sections (around 340 items) on a kanji meaning course I’m making have been completely wiped. I’ve written a bug report and began adding them back, since I don’t imagine the bug report getting any attention any time soon, but has anyone else had any issues like this?

It’s incredibly disheartening to put a bunch of time and work into a course, only to have a major part of it vanish, suddenly.