Almost all slurs suddenly missing from second half of score

A few weeks ago I got a popup when opening or closing my score that it had been corrupted - some time signature stuff that I think happened as a result of an incomplete measure I had added. But the bigger problem was that in any slur occurring at the beginning of a line had been distorted to stretch across multiple lines or even pages. Other slurs appeared a bit distorted but not as badly as the first of every line. I went through the entire score and deleted the distorted slurs and entered in new ones. My score was fine for several more work sessions and several times of saving, closing and reopening after that. Then today I noticed that for the last 25 pages of my score all of the slurs are suddenly gone, except for the ones that are at the beginnings of lines. This will be a lot of slurs to write back in, but I can do that. I'm just concerned about something having gotten messed up in the file when it first became 'corrupted' and how that might continue to manifest as I try to clean up one problem after another. Is there anything I can do about this? I have put a ton of work into this score since I corrected the first problem with the slurs so returning to a previous version is really not a good working option. Has anyone experienced this before? Thank you!