I've searched the archives and see there are a number of posts pertaining to smart groups not saving criteria, but it seems those were bugs addressed in updates, and we are running the latest version of CiviCRM (5.9.1).
I have smart group made up of organizations whose membership is current (our memberships are company-based). However, I can't get the smart group to save the "Is a current member" search string. Instead, every time I update and save, it drops that setting and goes back to just "Contact Type In Organization" as the only criteria. This happens regardless of how I try to create or edit the smart group - it drops all selections from the Memberships tab. Is there a known bug or some other issue that could be causing this?
Edited to add - the smart group count is also not updating when clicked - all of the smart groups still say "unknown." Could this be a caching issue?