This has driven me crazy several times in the past months (@florian-h05 can sing a song about my curses) and I never found a solution. If it happened NONE of my rules were executed.
I even debugged deeply into the core (which only revealed that the item changes ARE detected (“Item ‘xxxx’ received command ON”) and the scheduler does submit rules to be executed but they then get never executed by the java scheduler).
I never really found out a good reason why it eventually worked again. Once it was that I switched on and off debugging (jpda). Sometimes clearing cache or rebooting helped. The day before yesterday I was almost stuck but then found out that one manually added binding was missing a dependency which I noticed by an exception in the very beginning of the logs during startup. After I replaced it with the right binding file, all of a sudden even my rules worked again.
I am aware that this doesn’t sound like a systematic approach but at least I wanted to share my tries. Maybe at some time we will find the real root cause.