I use Delay in several rules, and they all hang on the delay. I created a simple rule to test and confirm. Testing including disabling the Delay to make sure everything else works. This started only recently (a few weeks ago?). I did a soft reset, but that didn't seem to help.
My first thought would be simultaneous instances creating mayhem if this isn't controlled by private booleans. A wait for elapsed time would probably be a better option for this type of rule.