Useful advice:

1) Are you sure that the critical diagnostic actually prevents e-filing? A lot of them don't.

2) Generate the CO 0102, print it to PDF, attach the PDF to the CO e-file, remove the Form 1310 entries. Alternatively, apply the CO refund forward to 2022, when they won't have this problem. (They'll have a different problem, because CO is going to stick that refund in the deceased spouse's name, but the returns will e-file just fine both years.)

3) Disable e-file error checking and see what gets accepted.

Hard truths you are unlikely to appreciate:

4) We have to tell clients that the e-file rules are sometimes stupid, bureaucratic, and unfair all the time. Sometimes bad things happen to good people. This is particularly true when someone dies, because pretty much everything about death is stupid, bureaucratic, and unfair.

5) Ain't no one going to be attempting to fix anything this late in the season, in large part because every update carries a non-zero risk of breaking something else. That sucks when you have what seems like an obvious, easy to fix thing. For me one year, that was "the supporting schedule Lacerte is producing doesn't foot."

6) You and your client have known for 9 months now that they had a tax return due this year. Here it is September already; they can't be too desperate for the money.