Flight credit is based on the MP rules for the operating carrier. The fact that it is marketed by MU is of no consequence vis-a-vis mileage credit.

So, if you don't get MP credit for flights on FM (and I believe you don't), then you don't get credit for a flight on FM which happens to be marked by MU (unless it is opaque code-sharing (a China thing?) which I don't think it is).