Hello,
I have a trouble with the grinder because it's grabbing drops and kill mobs but it doesn't produce mob essence ... I don't understand because yesterday it works but today when i'm reconnect to FTB, it doesn't work ...
I use Direwolf20 with Minecraft 1.7.10...
Thank you to help me to solve this problem.

It's really weird ... i restart the game and it's work !...

There is a bug somewhere i think ... i give you my logs if you need (maybe another mod which is in trouble with ?)

Sorry for with issue, the bug doesn't not appear anymore.
Thank you and good job !