>OK, so please describe again, in as much detail as you can, what do
>you do with Emacs between correct display and incorrect display. You
>said you switch to another buffer and return, but could you tell more?
>Just switching to another buffer and back immediately triggers that?
>Or something else is needed?
That is indeed the tough part. I have yet to find a definite repeatable pattern that induces the bug. But, I now usually arrive there in a few minutes of activity with two emacsclients -t in use.
Switching back & forth immediately will not do it. At least one client is loading / unloading various files before switching back to other client. Take a look again at the original post for more of these general actions I use.