Custom filter table: Error alerts not always shown

Reproduction & observed behaviour

1. Try adding an invalid filter (for example [test])
2. Observe the error message in red below the filter table (Filter lists headers aren’t allowed here}
3. Add a valid filter (for example test)
4. Try adding an invalid filter, that should trigger the error message again (for example [test])
5. Observe that the error message in red below the filter table does appear, filter can not be added, there are no errors in the console and no feedback is given to the user

Expand for .gif of the issue

Expected

Error alerts should always be triggered within the sessions, when trying to add a forbidden filter.