Mana leech problem only with runic monster

Have character that build toward to mana leech
- Mana leech from attack : 1.91%
- Total mana leech per second from leech: 232.25

Setup is working fine with non-runic monster (in Map or Boss), but with runic monster it keeps empty and not able to leech.

As my understand that runic monster having Ward, is it mean the damage on Ward it not leechable?

Note: it's not always happened. When it does, leeching won't work and only natural mana recover

Thanks for helping, didn't aware there is such mod.

No wonder it happened.

Cheers.

There are also some monsters that leech mana from you. This can make it appear like your mana leech is not working.

These mana leech monsters were causing me instant death (as a mana based cyclone character). I believe it is one of the warlord's minions that do this. I adjusted my skill gems to include lifetap which solves the problem for me, but likely is not an option for others.

I think there is a helmet corruption that can prevent monsters from leeching mana from you. There was once upon a time a passive that provided this but apparently it is gone now ... yet the enemies cannot leech life passive remains. There is exactly one [unique] item that provides the ability to prevent monsters from leeching mana from you.