supertech,
First, did you make any deductible IRA contributions at any time in the past? In that case, some of the Roth conversion is taxable by the IRS.
With respect to Massachusetts, looking at the instructions for Form 1 (https://www.mass.gov/doc/2021-form-1-instructions/download) there is a worksheet that starts at the end of page 19 which may be a clue. If lines 2 and 3 are zero, it would treat the amount converted as taxable. I do not have the MA state add-on, but dig around and see if you can find where to enter/adjust these fields. If you can access Form View instead of Step-By-Step, go to MA Schedule X and try to edit the second line of it.
