I am filing "Form IT-40PNR, Part-Year or Full-Year Nonresident" and all of my other Indiana schedules are supported for e-file. I filed all of the same forms with TurboTax in 2020 with the exception of "Schedule IT-2210, Underpayment of Estimated Tax by Individuals." I doubt that this form is the issue, but it might be worth checking. It's worth noting that TurboTax claims that there are NO errors in the Indiana return, and claims that the Indiana return is eligible for e-file.
As mentioned by others, "Form IT-8453-OL, Declaration of Electronic Filing" is not supported for e-file, but that's because you do not actually e-file this form. You are supposed to print this form, sign it, and keep a copy in your own records. During the Indiana State e-file process, TurboTax displays, "You are signing your return on paper. We'll take care of printing the form you need *after* you e-file." I believe that this is in reference to this form. See this discussion for more on Form IT-8453-OL.
https://ttlc.intuit.com/community/taxes/discussion/after-e-filing-my-state-return-with-turbotax-i-re...
Having said that, it would be worth checking with the programmers to ensure that a return's inclusion of Form IT-8453-OL is not causing the e-file transmission to fail.
