B5 Win 10 x64 Brief; I think I've seen this in v20 so it may well not be new. Very occasionally SE gets itself into a state where if I try to edit the code I jump to a different section of the code. What I think has actually happened is that the text displayed on screen isn't in fact where I am in the code and when I edit then the screen updates to reflect reality. Once in this state it has a tendency to be prone to the issue until shut down, but restarting SE always seems to clear it. I can't generate this on demand I'm afraid.