NONE.
Actually, this surprises me, because when you indicated that you did not have HDHP coverage at any time in 2020 (you did do that, didn't you?), this should have set every part of Line 3A to None.
Perhaps once you entered the 1099-SA, you left the HSA interview without doing the rest of the interview. You really should go back and do the whole interview.
Note that this may cause the Line 1 thing again in the Review, but you now know to mark that as Self.
You should not see the Review complaining about the Line 3A boxes.
Note, you and your spouse (if one) will see a question, "What type of HDHP coverage did [name] have on December 1, 2019?" (yes, 2019). When you see this question (whether once or twice), just answer it NONE.
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