Y issue?missing step?

My MPcnc is wholly from V1. I just transitioned from printer back to CNC and I’m getting these uncut sections on the uphill(?) path in my X. Does anyone know where to start looking? Image attached.

Do you have the correct bit width and overlap configured?

It cut with a correct overlap on the right to left pass. I’m using the default 90% overlap and it’s a 1/4" endmill. I tried slowing down the feedrate, same result.

doesn’t 90% mean that it’s cutting 90% of the bit width of new material?

Most of us use a 1/8" bit with no more than a 45% step over. You are putting something like 4x’s the load on it.

Then I’ll stop doing that and expect better results. Thank you for your help.