In the past, and also earlier this year, I e-filed Form 1040NR's, including NR state returns for CA and AR, with no problem0.

I just finished a late 2020 Form1040NR with Hawaii Form N-15.

The Critical Diagnostic Warnings include:

e-file: Nonresident alien or dual status alien returns are not allowed for e-file.  A nonresident alien or dual-status alien return must be filed as a conventional paper return.  (ref. #51788)

Was the e-file availability for 1040-NR changed?  If so, when did the change take place?

Or, is it because the return is late?