we don't know what the CPA did but there had to be a formal statement in the 2020 return electing to carryforward the NOL. no such election then you need to c/b the NOL to 2015. it may be that the CPA never prepared the carryback claims. if you don't see it maybe call the CPA to ask. if this was a mess up on their part you may want to see a lawyer about filing a malpractice suit.
I'm not sure TT can do a c/b claim to 2015 since that app is no longer available. as a matter of fact 2016 and 2017 are not available either. you may need to see a pro to properly file the c/b claims.
