I made a short video to show the problem in action: https://youtu.be/ksAf4cgC7xE
In both halves of the video, I left click to move straight upwards and then spam click to open a UI window with the keyboard.
In the 1st half, it’s the Character screen, and everything works fine.
In the 2nd half, it’s the Inventory screen, and it’s immediately apparent something is very wrong, and even interrupts movement completely.