I just spent over an hour battling against Unity, trying to prepare and re-use my main menu and pause menu from my previous Ludum Dare entry. Apparently moving from 2019.3 to 2020.1 breaks a lot of things in what should be just a simple export-import routine...

Oh well, this is why you prepare things like this ahead of time, so you can use your jam time actually making the game, not fighting against your tools.