Have you filled out the Schedule NR, where you show the percentage of income sourced to Maine?  Like some other states, Maine tells you to figure the tax on all of your income, regardless of source; then figure the percentage of your income that is taxed by Maine; then multiply the total tax by that percentage. 

Taxpayers whose total income will put them in a higher state tax bracket, will pay more tax on the same amount of Maine income, as taxpayers in a lower bracket.

What entry do you have on Line 21 of Form 1040ME ?

"So I guess there's no point in subdividing the W2 income by state in the W2 entry, even though the W2 splits it."

Maybe a ProConnect user can answer that.  ProSeries uses those numbers to make allocations on part-year and nonresident splits.  

@kenhoyt  Did you indicate the resident state in the very first entry in the General > Client Information?

Did you indicate a multi-state return in the next entry in the General > Client Information?

Is this how you allocated the wages? https://proconnect.intuit.com/community/help-articles/help/entering-w-2-wages-and-withholdings-on-mu...