Blights seem to cause spell and ability timers to stop working. one of their myriad of debuffs is probably making this happen.
can it be looked into futher?
for example, i will have some of their debuffs on me, click engulf at the target... engulf will miss or hit, and the recycle will stay grayed out for a long time. Sometimes have to rekey the hotkey to make it start the countdown.