Thanks Troester for investigating this!
System cache is disabled. Tried also disabling list cache in list settings, no change.
It is with standard fabrik menu item and also with related data. Tried playing with "Reload calculations" and "Reload filters" in menu item settings clearing browser cache in between, still same. Also tried removing "&Itemid=xxx" from url.
It is clearing the list filter ok (showing all the records), just the selection remains in the dropdown filter element if that's what you mean.
Also played with list filter settings (under heading, above, disable search all and advanced search), no luck.
Seems not to be dependent on Fabrik version. Same behavior in Fabrik 3.5.1 and 3.9.