Brutu's Brain gem not active on cleric minion

Anyone know why the "Brutu's Brain" support (minion can not be damaged or do damage) is not active on the cleric minion? I do have enough support gem capactiy for it to be active and above level 65 already.

Do you have +stats on your weapon/offhand? do you still need them on your second weapon set to make it active?

I have had similar issues, but as I only use 1 weapon set I could use the function to copy primary weapons to secondary, then the stats work on both sides