What are you subtracting?

Other state income. I called Intuit , the remedy is to attach the M1M form and proceed with e-filing, ignoring the diagnostic.

Other state income?

I rarely encounter this so I may not be thinking clearly, but why would you subtract other state income?  And on what line of the M1M are you doing that?

"I rarely encounter this"

I've never encountered this so you are ahead of me on the experience level.

I have less experience with this than either of you, so I had to look at the MN forms instructions. Apparently the MN DOR isn't familiar with it, either.

Luckily support is familiar with it 😳