Hi lechoo, first of all , you are wellcome.
And i think it is no problem to ask in englisch, we try to give you answers.
But in this difficult case , hmm its difficult, i cannot remember the settings of muhair, but i think this thing you are trying collides with the settings of hair and fur and the muhhair shader, i guess that the muhhairshader is not able to render " meshed " hairs . One good example is the Mateditor, if you look at it
you can see the sphere with the same effect like your problem.
My only idea is, to avoid the button " turn to mesh "