Hello,
If the custom status of the thing type is set to empty with Set state [element, state_name] = <blank>, then an action’s conditional execution based on is empty and is not empty always resolves to is not empty.
I set up an example application: https://isemptyerror.bubbleapps.io/?debug_mode=true. The first button sets the status, the second button puts empty in it in the above fashion. After setting the empty state there are two send email actions with conditions on them linked to the state (is empty, is not empty).
The workflow always returns is not empty, regardless the ordering of both email actions
This might be a bug in bubble. If I set the state to empty with empty list (Search for without hits) the example works fine.