Thanks for the update. Seems like you're reconfirming what I thought might the case. Not a simple way to address this and that there is no efficient workaround through config or plugins at the moment. That's unfortunate. Well, I'll keep my eye out for if anything comes up in this area in future. I may try the search approach next as an interim solution if I decide to go forward with multiple, separate Series columns. Composite Series column doesn't seem to gain me anything so I won't be doing that.
As to your question...Perhaps my terminology was not accurate. I am new to Calibre. I saw that creating the column, created a category in the tag browser. Thought that was what was known as a User Category. Perhaps that term only applies to the ones that are created via the 'User Categories Editor' like Favorites user categories.
Right. What I stated above what just my attempt to try to implement the solution suggested and noticing some of the differences in how my custom Series columns seemed to be working in the tag browser vs. Author. Looks like I typo'd that.
btw...Just building my database now. Got thousands of books to input. Using it for ebook, audiobook, paperback, hardback, periodicals, fanfic, and userguide tracking. Love it so far. Seems to really help me find stuff easily. And use it for home insurance purposes as well. Catalog export works great to feed into my home inventory mgt software. We'll see how far I get.