Well, I've made some minor progress.

I painstakingly looked at every single detail on the General tab, and after noting an extra space here and there after the Album Title or Artist name, was able to coax 2 "wayward" discs to sync into the proper tree.

However, in trying to complete the tree on the 10-disc John Coltrane box set, cannot find any discrepancies on disc #10, so it's still in the wrong tree. It's exhausting and frustrating. Everything looks exactly the same, yet ...

Man, talk about the enigmatic nature of computers and software!

Your thoughts, Andrei?