When a try to move my comment (to another frame or within a workspace) it doesn’t move with my cursor, but “jumps off” instead. I have to press esc and then c (comments tool) again to try one more time and sometimes it helps. But not every time.
In any case, what you are describing seems like a bug, you should report it to Figma support team via the bug report form. You will be able to upload a video there.