Global flags always show up as false (i.e. not flagged) in views field.
Add a global flag and create a list of users with a field showing the flagging status.
Can be fixed by checking by overriding the render method and checking if the result of getValue($values) !== NULL in
Plugin/views/field/FlagViewsFlaggedField
Needs work
Views integration
The patch will have to be re-rolled with new suggestions/changes described in the comments in the issue.
The change is currently missing an automated test that fails when run with the original code, and succeeds when the bug has been fixed.
Not all content is available!
It's likely this issue predates Contrib.social: some issue and comment data are missing.