"why doesn't ProSeries have a 1041 option on the state products."

Because it doesn't apply, or doesn't even exist, or there is something else you are supposed to be using, instead, which may or may not be in that program. Have you looked here:

https://proconnect.intuit.com/proseries/forms-finder/

You know not everything is in that program, right? And it seems you are looking for a form that doesn't exist. Did you read the info I provided? That's why I gave the links.

"The fiduciary of a resident estate or trust must file a Form FID-3 (Montana Income Tax Return for Estates and Trusts). The fiduciary of a nonresident estate or trust must file a Form FID-3 (Montana Income Tax Return for Estates and Trusts) if the estate or trust receives Montana source income or if at least one of the beneficiaries is a resident of Montana during the tax year. A return is not required if the total income of the estate or trust is less than $2,580."

...

"The 2021 Form FID-3 must be filed for the calendar year 2021 or the fiscal year beginning in 2021."

...

"Unless the tax return is filed electronically, a fiduciary must include a complete copy of federal Form 1041 and all related forms and schedules."