Retirement tax questions

Thank you all for the questions/ replies. They are very helpful.
My situation is a little different:

I have been doing Backdoor Roth conversion for a few years. Then moved to MA in 2020. I had no issue for 2020 tax return as I was “non-resident”.

I have Never taken any distribution from Roth, and basis for Traditional IRA is 0.

This is the first MA return as an “MA resident”. 
under “ Taxable IRA distributions“, “other contributions previously texted by Massachusetts” - - my Roth conversion amount seems to be taxed by MA no matter I place “0” or 6000 in here. 

”Total distributions received in previous years” - - I have placed the sum of previous conversions , which I believe is the  distributions. 

could this be the reason?

how may I avoid the double tax by MA? 
Your help is much appreciated.