Since we can't see your return in this forum, we can only offer some suggestions.
There should be no issue Efiling with a Non-Resident Minnesota return, and a Resident Wisconsin return. Did you prepare the MN return first?
Here's some info on How to File a Non-Resident State Return.
Some common Efile issues include, returns that contain overrides, have no taxable income, or contain a W-2 where box 1 is blank or the box 16 amount is greater than the box 1 amount.
If you're using TurboTax Online, you could try deleting your state returns, closing TurboTax, clearing your Cache and Cookies, then re-creating your state return.
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