Thanks I found the issue, it wasn't my mouse or USB devices, I'm using a razer viper, but I don't have Synapse installed. It also wasn't the X-mouse button control macro program I was running, I also was using no mods. The actual issue appears to have been the Windows Japanese IME, I'm going to post a screenshot to show what setting to use in order to fix the problem, the IME is still in beta and a change to it must have been the cause as far as I can tell. I never would have thought to even try this out if you had not mentioned the keyboard macro. Bizarre bug, bizarre fix, I'm grateful to be able to play again.