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OMG I got it. Animation was a good point. I forgot to remove the "has exit time" in my animator controller transitions. Now it works perfectly fine. Sorry for the trouble and thank you very much! :)

Good point. But the animation curves are linear and the whole animation only lasts 0.25s.

Thanks, Lazlo. I am glad and grateful that you were able to identify the problem. :)

Hey Lazlo Bonin, thanks for merging the 2 topics. But I think my posts got deleted :(

This happens only the first time I enter the trigger. If I re-enter the trigger area the event gets fired immediately.