I am playing assassin in Sirius and have a really bad bug going on. It happens alot that my skills and pot are being used but no effect is happening. Like i use minor, it takes 100 MP but does heal me. I use spike, it uses the skill but no damage at all. I use soul but no mana recovered. Most of the times it happens when i am below -50% hp. But can also happen over 50% hp.

How do I fix this bugg, anyone knows ?