I figured out -my- problem.
In the 1099K interview, it asks you to enter the total proceeds for items sold at a loss or no gain. I believe this amount needs to be subtracted from your overall sales - as you can't claim a loss.
Check out the form "1099K Summary". You need to reconcile your transactions to the total Schedule D "net amount of payment...transactions after adjustments" number. You will notice that this number has been reduced by what you entered in the prior/above interview question. I was (apparently mistakenly) trying to hit the gross amount from the 1099K. Once I matched my transactions to this number, I was good.
Hope that helps.
Once I mapped my sales to THIS number, it went through.
