Since the last release, the timers do not cancel or get reset when motion is detected, so after an hour, the lights just start turning off for every motion that was senses 1 hour earlier.
This has been reported here and is being investigated:
I'm not sure if it will make a difference in outcome (with respect to this problem -- it won't normally), but in your rule, "Cancel Timed Actions" is overkill and a simple "Cancel Delayed Actions" would work if you have not tried it that way already.