Are you saying that you lost data during the upgrade to 5.5? I hope you backed up your site.
My only guess here is that you’re options, for some reason, got moved to the termmeta table when upgrading the database…. but ACF does not delete the existing values, so even if they were copied to termmeta they should still appear on the options page, there should be no reason that they would have been deleted. Did you follow any of the advice in other topics here about deleting data from the options table after upgrading to 5.5?
I can confirm that I’m seeing the same thing shown for the collapsed value showing the field key.
