Guild Wars 2

I put a Demon Summoning into my Molten Greatsword. At first I got the stacks and summoned the fleshreaver, no problems. After the fleshreaver died, I no longer get stacks for killing foes. Changing maps doesn’t fix it, only logging off and logging back in will allow me to start getting stacks again.

I am having the same issue, i added the sigil to a staff, and it only works once. I played for a couple of hours killing hundreds of enemies, and after the first summon, the sigil no longer gains stacks.

Edit:
It appears that there is a very long cool down (hours) which is quite ridiculous since the summoned fleshreaver only lasts 60 seconds.