RSIBreak doesn't prompt for long breaks

Short breaks work as expected, if there's a pause in activity equal to or longer than short break duration it counts as a short break.

But long breaks mostly don't happen, no popup or any notification shows up. In Usage Statistics the Last long break item is either empty or shows a time long ago and is red. Right now a long break hasn't happened in 1 hour and 52 minutes (it's set to happen every 45 minutes for 10 minutes).

I have set it to take activity into account because I want long inactivity to be treated as a break.

Anyone knows what the reason might be? Is this the expected behavior?