Had to remove 1095-A since changing to "can be claimed" caused a review error on SS number field on 1095-A.

Amazingly starting over for the 5th time worked and got it filed!  Here's how with comments:

1. Before opening any other forms, went straight to 1040x and checked "2021" which only caused only the original refund amount to be transferred to Section A of 1049x.

2. Marked "File Amended Federal" and "Original federal e-filed"

3. Changed "Claimed as Dependent" and "Was claimed" to YES

This time did NOT indicate WITHDRAWAL for amount due (will get bill presumably) since a previous attempt had a message "cannot do withdrawal when refund due" because the 1040 now shows a different overpayment...

Waiting to see if accepted by IRS!

None of this previously made sense and no suggestions helped, but thank you all for trying!