The site in question displays a table-formatted View of relevant content, with a checkbox column for flagging. [relevant modules installed: Flag, Flag Lists, Flag Actions] The Flag List Operations widget allows creation of custom-named lists, which are viewed in a separate node. Each list name launches a full display of the flagged content. At one point this was working perfectly for authenticated users as well as for Admin. Mysteriously, now it is working for one authenticated user but not for any other authenticated user. Specifically, these other users' List names will be shown in a table view, but when clicked, the list is empty. I tried deleting the non-working users (all experimental at this point) and creating new ones. There is no obvious difference in the config of the new ones as compared to the one that works. Any suggestions about how this inconsistency could happen?
I found a solution to this problem, although I can't say I fully understand why it was happening. Seems to be a case of too many relationships in the View, causing some type of conflict that appeared only in some cases. During the building phase I had added a batch of 6 relationships, trying to get it to work but ended up with more than were necessary. I eliminated them one by one and tested, until the truly necessary ones were identified. It really only needed 2: "Flag lists: User" and "(List user) Flags: User's flagged content (current_user_flag)."