Query tag alarm issue

Ignition 8.1

Hi All

I have been struggling for with a strange alarm issue this afternoon. I have a simple query tag that returns a scalar. I wish to generate an alarm if this scalar drops below a setpoint.

I configure the tag and then the alarm as required.
The alarm will not fire.
I go back in and change the SQL query (e.g. add or delete a space)
The alarm starts functioning as expected.

If I change the alarm configuration, e.g. assigning a pipeline notification, then the alarm will stop functioning. To recover, I simply modify the query string as above! Note, that the query is not affected and is always valid.

Please can someone help me fix this? Is it a bug or have I missed something?