When I possess a character BP, it works but then my mouse input is ignored unless I click and hold down my mouse

Like the title says, I firstly possess a pawn, which is not doing anything because it is for main menu. Then when I click START, I can successfully possess the character in game and walk around with the WASD. However, the mouse is ‘ignored’ unless if I click and hold down my mouse, then I can look around. Weird bug or did I do something wrong in BP?

Oh yeah, I forgot about that. I tried ‘Set Input Mode Game Only’ and it still doesn’t work.

I got it… I didn’t make the get player controller into a variable, and straight using it from the ‘get player controller’. It works! When it was a variable, it ‘accessed none’. Don’t know why though. Thanks!