Toolpath seems to go off course - but consistently, and even in simulation!

So i cut some parts, quickly, and the inside of the letter “B” didn’t properly follow the contour. The weird part is that it was consistent to the point that it seemed like it was designed that way.

I went back to aspire to check it out, and everything looks normal, and the aspire simulation looks great.

When I pull it into mach3 though, look at the path it takes. One weird thing is that if I run through the toolpath slowly, it doesn’t do this. Notice when I run in reverse (second half of this short video), the same problem occurs but in a different spot:

Any idea why this is occuring? It shows up in the part as well:

Note - you can see the proper toolpath right next to the flaw, because later I did a pass with a v-bit to bevel the edge without issue.

EDIT: Here is another short video of it running at a slow speed - no strange behavior!