Mecanim and script behaviour issue

I've encountered a problem with Mecanim and a script which is attached to a state. When I press play and start testing my state machine everything works fine besides one state. Mecanim enters the state but the script attached to it isn't called (testes with a Debug.log(...) inside the OnStateEnter() method) It works in every other state and I recreated the state several times but the issue still persists. The animation speed of this state is set to 0.2. I tried the following:

If i mute the default transition, which is used if no trigger is set, so the state persists in its current state and can only leave if the trigger is activated. In this case the OnStateEnter() method is called every time.

If i press play and it is not working as always but i change the state speed to any number ( yes any number including from 0.2 to 0.2 in which case no obvious nothing changed at all) it works like a charm every single time....

especially the last part brought me to a point where i can'n figure out why Mecanim would behave that way and i hope somebody could help me....

thanks in advance