Hey @alwayslearning - sorry for the trouble here. I think I know the source of a few of these issues, but I need a bit more information to be sure.
First, a little background on how we handle your files in Roon-- what happens is that each file you import into Roon gets a signature in the database, and Roon should be able to track that signature if you move the file to a new location, or even if you rename it.
It’s important to note that it’s of course possible to have more than one copy of a given track in your library, and Roon will track them both (along with their associated edits, playlist appearances, play history, etc).
Here’s the issue; say you have all your music in a network. Then, you make some storage changes, and now Roon thinks this folder is “temporarily offline” – this is when you’d see DirectoryNotReady. Because the directory is still configure, and Roon isn looking in the old location, the app MUST assume those files are coming back.
What you want to do is tell Roon those files are moving elsewhere, by editing the folder and pointing to the new location, or by removing the folder from Roon completely. In either case, all the files would be marked as “missing”, and when you add the folder in its new location, Roon would recognize the file signatures, match it up to the database, and re-attach all your edits, playlist appearances, etc.
Instead, if you leave the directory in that “temporarily offline” state, when you add the new folder, Roon is assuming the first location is coming back, and so all the files are considered to be new imports. It’s a bit complex, but it’s designed to be robust and allow for the movement of files to new folders – it just needs to be done the right way.
What I would recommend at this point is that you remove all storage devices in Settings, and once your library is empty, re-add just the current folders. Unless you’ve been making additional edits in the last few days, I think everything should be right where you left it, although feel free to load up the backup from a month ago if you want to be absolutely sure.
In regards to your other question:
I can tell you that we’ve seen other users struggle with similar with the performance of Apple’s SMB implementation, but we have seen this work. I am wondering why you don’t just run the Core on the iMac, if that’s where you intend to connect the USB drive. As a general rule, directly attached USB storage is going to be a lot simpler and more reliable than what you’re attempting here.
Let me know how the above sounds, and if you need some more details on any of it, and we’ll be happy to help. Thanks for your patience so far!