My mind is blown. I wish I had found this thread a year ago so I didn't head into this endless loop! I think I now know how to handle my amended 2017 return thanks to this thread. So big thanks to the contributors here!
If any of the rock stars are still monitoring this thread, I would love a thumbs up that the below interpretation is correct:
In my scenario I didn't know I could mock up a 1099 R back when filing my 2017 return for my distribution of excess contributions in 2017 (and was incorrectly told by my investment guy that it would just be taxable in 2018 anyway) so I'm now entering my 2018 1099 R that I just received on an amended 2017 return and finding that I have a small additional excess contribution ($60) now because of the small earnings ($111) from the original excess changing my MAGI which is within the phase our range. I think I need to sell the new small $60 excess and earnings on it now and mock up a 2nd 1099 R now to include on my amended 2017 return along with the 2018 1099 R I just received for the first sale of excess contributions last year....I'll read the 2017 instructions for 1099 R to hopefully get the codes right on the mock up, but its a bit confusing to me handling both 1099 R forms on a single amended return.
