Warlock Malefic Rapture not working

[drashai]

WoW Freakz spell link: https://www.wow-freakz.com/spells.php?spell=324536 (wowhead link)
Character name: Steuntrekker
Bug description: Malefic Rapture not working with corruption and voidwalker summoned
Proof: When I have my voidwalker summoned and corruption is on the target, malefic rapture won't cast and says i don't have a periodic spell on the target. Its working fine with agony. And when I dismiss the voidwalker its also working again (with corruption and agony). Anyone else had this problem and have a solution? Yesterday all was working fine.

[Ph3n0]

So it's like this:
If target is attacking someone else than than you(tank, voidwalker, etc.), you can't cast Malefic Rapture.
If target is attacking you, then you can cast normally until dead or it switches aggro to someone else.
If one of multiple targets is attacking you, you can cast malefic grasp until that target is dead or switches aggro to someone else.
As long as you are "tanking" something on you, it works.
Another unplayable or bad lock spec...