Greetings @CleoLan !
We see that this is your first time posting in our forums! 
Welcome to the Unreal Engine Community!
Iām sorry to see that you are having issues with your character. Iām reminded of a post I read where a fellow member had the same problem. Feel free to check out this link and see if any of the suggestions can assist you with what is happening to your character, and please let us know if this helps! Happy Creating! 