Ties are completely messed up

I just opened up a MuseScore file I hadn't worked on in a while, only to find out that the ties I placed into the second half of the score score were all sorts of messed up. They were attached to notes multiple measures later, making random notes in the middle not play, and even hovering on their own without being able to be deleted. I meticulously went to the effort to fix them all, but as soon as I started working on anything else they all came back and wouldn't go away when I pressed undo to just after I fixed them. None of my other files have this problem, and it doesn't go away after closing and reopening the file or MuseScore altogether. Here's a screenshot of just a little bit of the insanity:

I've attached the file to this post. I don't know if this is replicable or if anyone else will be able to see it on their end. Yes, the file is big and complicated, but I have an even larger file that works just fine, so that's not the source of the problem. Four_Part_Harmony_(mainly_original).mscz