Hey! I see this a couple times in old issues, but I am not sure how to fix. It happens when I have optifine installed... I removed optifine from my mod folder and things worked as expected; put it back and it messed up again. Here's my debug log from after I added optifine back:

https://pastebin.com/CUmA34a1

Any advice appreciated!

Fixed in 5f91e4e

Hey, so turn off virtual controls, and it's good. Obviously you're now in control of the real mouse so you can't split screen or something, but at least I can solo without issue and can quit researching optifine replacements.