I haven't had this issue happen until today when I had another game running. If I close out of the other game, Minecraft goes back to working properly. If I launch a different game with Minecraft still running, the cursor begins to leave the window again. This happens in fullscreen, borderless window and windowed in all combinations between Minecraft and the other game, the "other game" can be all types of games and Minecraft responds the same way by allowing the cursor to leave the game window, making Minecraft unplayable.
Andrew Granheim
I haven't had this issue happen until today when I had another game running. If I close out of the other game, Minecraft goes back to working properly. If I launch a different game with Minecraft still running, the cursor begins to leave the window again. This happens in fullscreen, borderless window and windowed in all combinations between Minecraft and the other game, the "other game" can be all types of games and Minecraft responds the same way by allowing the cursor to leave the game window, making Minecraft unplayable.