Do you chart?
Did you see the dozens of charts I put in my signature? Including my WIP, I've made almost 50 charts, all in EOF.
Go to the last anchord, and create a new one 2 or 3 beats away
I could not reproduce this either by using Beat>Anchor Beat or Toggle Anchor, and I've tried multiple charts. If you are even at least able to use print screen to take screen captures (before and after the problem occurs), paste it into any image editor (even Paintbrush) and email it to me (preferably with an EOF file and instructions to reproduce the problem), I can send you my email address in PM. If you can't use email to such an extent, then I don't see how we can help identify whether this problem is reproduce-able outside of certain computer configurations.