Unwanted stepped carve

So I’m working on some small signs made out of MDF and I typically don’t have very many issues when carving. If I do I can usually work my way through it and figure out a solution. So the problem im having is when I’m carving pocketed letters i get steps within the carve, see attached picture. Sometimes when it happens I will just exit out of Easel and restart my computer, usually fixes the problem. However, this time around I’ve ran several passes on the carve, with two different bits, and having the same problem. I thought I might be able to adjust the depth of cut and it fix it but nothing. I watch the carve as it gets to the problem areas and it looks as if the router comes up ever-so-slightly but the pulleys are tight and they do not move when it comes over these areas.

Any help is appreciated and thanks in advance.