I am having the same problem. There is a spot on the MA form questioning what the "Other Contributions Previously Taxed by Massachusetts" is.
I went through the steps for the backdoor contribution (https://ttlc.intuit.com/community/entering-importing/help/how-do-i-enter-a-backdoor-roth-ira-convers...) and once I entered the contribution to the traditional IRA, the Federal form removed the taxes as expected. MA did not. The backdoor Roth conversion is more straight forward without having a previous traditional IRA from previous years as there would be a prorated conversion. I had no prior traditional IRA and the federal form is good. I then did the above step after regoing through the MA form questions.
