How do I properly enter information regarding the partner-to-partner sale of a partnership interest (Class D Incentive Units) from my LLC employer? No 1099 was issued.

I received Class D Incentive Units at hiring in 2017 at no cost to me. It was an incentive. In 2019, after a change in ownership, I sold a portion of them back to the company for x-amount. I did not receive a 1099 and was told by our General Counsel that I should report the sale as a partner-to-partner sale of a partnership interest, for which there is no 1099 reporting. I'm no tax accountant but an account at work told me we need to submit form Long Form 8949 to report capital gains. However, for just about every question the form on TurboTax asks, I don't have answers. Can any of you please point me in the right direction?