Hey kokostas2001!
This might sound stupid, but it looks like you’re setting your input mode to UI only in your level BP this is going to disable your characters ability to move when you enter the level. If you’re setting your input to UI only without resetting it with another event, your char will be stuck in the UI only mode which will disable your chars ability to move.
If you’d like you can PM me your project and I can see where the errors are.
Hope I can help more!
Entro