Local Files Disappearing

[ashtinskronson]

So, I've used the local files feature for quite a while. I have mutiple playlists of music that isn't on spotify, for mobile listening. This has worked fairly well in the past, all things considered; we all know the local files interface is not very user-friendly, doesn't allow editing, and rarely treats file information correctly, but I'm used to these frustrations by now. I've had it pointed to a specific folder and it would always update immediately whenever I add files to the designated folder.
Today that went all screwy when I added around 8 albums throughout the day and changed the source location to a smaller folder within "My Music" in order to eliminate some duplicates. Some tracks are still listed but unplayable, other tracks are suddenly unlisted, others are listed even though I deleted the files from my machine, and a few are just as fine as they have always been. I'm not sure the exact chain of events but I'm certain this problem cropped up as soon as I changed the source folder. I've been moving my files to various sources (including the itunes folder where I had to fix some track names and also back to the global My Music section that has always worked fine), changing my preferences to reflect the changes, and still.. a huge chunk of my local library just refuses to index. These are nearly all files that have been played many times before, so it is not an issue of format or bitrate; and though some albums are entirely absent, there are also albums that only partially indexed. I have tried closing and re-opening the app, logging out and back, moving the files around all manner of ways, and just good old-fashioned waiting for a refresh. I suppose I could try uninstalling/reinstalling but I don't know what I will lose with that process and I cherish my saved collection so I figured I should ask here about that too.

running premium, version 1.0.66.478.g1296534d
on a mac pro with sierra 10.12.6

please be respectful and please read the details carefully. thanks for the help, anyone!