There is an issue with re-importing DVD rips that has been around since MC17.
It isn't a bug. That's just the way it is designed. All IFOs import as [Media Sub Type]=Movie.
You could argue that it shouldn't be that way, and I wouldn't necessarily disagree. I think it is likely because doing the full "Carnac" thing on DVD rips isn't practical, or would be very slow (parsing IFOs isn't speed-racer quick). In any case, all IFOs import as Movies. That's the way MC has worked for a long time.
Another thing: I have a movie called "THX 1138" in my collection. Often when I check the tags, JRiver puts the THX into [Series] and I have to correct it manually. All files are stored in mkv and saved on a NAS. JRiver is on a Win8.1N x64 / Admin User system.
I still don't understand tyler69's issue. Please explain if you only see this behavior with newly imported videos, or if it happens to videos already in your Library.
"THX 1138" is, depending on the filename, probably one that might confuse the Carnac logic while it is being imported. It should be recognized as a Movie, if the file duration is long enough, but perhaps something else is going on there.
But, if you've already imported it, fixed the tags, and
then MC is changing things you've manually entered after the fact, then something else more serious is going on.
If it is the latter, I'd guess that at least a portion of your Library is getting cleared somehow, perhaps by the Fix Broken Links feature. In any case, we'll need a lot more information before we can help.
Please describe in MUCH more detail what you're seeing happening. If your post isn't a few
paragraphs long, you're not including enough. Giving specific examples, including filenames on disk, and the exact step-by-steps of what happens is essential. Including a
screenshot or two might not hurt either.
Thanks.