Withdraw Excess Roth Contributions at a Loss

I realized that in 2019, I contributed too much to my Roth IRA.  The value of the IRA has declined since the contribution, so when I withdrew in 2020, I took out the excess contribution minus the associated losses.

 

I entered into TurboTax that I am planning to fully withdraw the entirety of the excess contribution prior to the tax deadline so they do not add the penalty.  However, given that I won't receive a 1099-R until 2021 (due to withdrawing in 2020), I'm unsure of what to enter in the "income" section? 

 

Should I be entering a "dummy" 1099-R so I do not have to file an amended return later on? If so, given that I am showing a loss, what do I enter in box 1 (excess contribution minus the losses, or just the excess contribution?) and box 2a (can I enter a negative number for losses or leave it at $0)? What codes should I use for box 7?