There seems to be a lot of mouse issues for me. I have to alt tab to get my mouse to be able to be moved. I have to jump through hoops to get it back into the game window too at points. Even after hitting T, the mouse is stuck dead center.
I had this issue happen in game test's once, But it has not been a constant issue, maybe try a download or close and reopen, ill have a update out soon, hopefully that fixes it, please let me know how you go :)