Hi, I'm on the most recent IWBUMS but I had this same issue on the stable version. Whenever I right click, it brings up a menu as usual. Unfortunately, usually the top option on the menu is unclickable. This won't let me place sheets or do anything requiring the use of the first option when right-clicking. When I attempt to click the first option, nothing happens, and the game starts to get massive FPS drop. Windows 7 SP3, Scaling disabled on High DPI (it was a workaround until the IWBUMS update)