Using custom boolean attribute not working

When a choose a custom boolean attribute I am never prompted to choose an operator:

Because of this I can't complete my rule. This is latest 2.1.7. Anyone else having issues?

Can you show a screenshot of the edit device page for 1st Floor CO Detector? If the attribute low_battery is not displayed in current states you won't be able to pick it from the list to define it.

Thanks I totally forgot about this! Was it ever resolved?

nope, but I was looking for the same answer and figured I'd at least contribute by answering with what I found. I ended up using enum.