I encountered this same problem. I ended up deleting all the entries and starting over but using the mode where you fill in all the numbers. When I was done, it was still showing too large of a capital gain - it tells me that it has adjusted my basis by the bargain element (which was included in my W2) but what it puts into schedule D is still *wrong*.
So, I'm seeing two bugs: Second pass through still shows info from the first sale and even if you get everything in properly (manually) it will tell you your basis was adjusted but it was not.
I think the best I can do - since basis was not reported - is to calculate this entirely myself and enter the corrected basis and ignore treating it as a sale of Employee Stock.
This has worked so well for years - I wonder why they broke it for 2020?
