Can't turn off Sort Siblings

[FlagTech]

After invoking Sort Siblings in the tree, now I cannot turn it off--i.e., the checkmark in the popup menu stays checked regardless of clicking on it.

This is happening in a tree branch of Contact records. So I tried selecting the Sort Siblings option in a different set of Contact records (I have a couple of them in this UR database), and now it is stuck in the check marked state also.

I've exited UR and restarted it; no change.

This wouldn't normally be a big problem, but I've just imported several hundred contact records and about 1/3 of them need to be edited (due to the data source, not UR) in a way that affects the Title Expression result. So every time I finish an edit, the record suddenly gets moved to its new position in the sort order and I "lose my place" in the group of records I was editing.