"with the gross proceeds and the cost/basis have the same value"

Just to review, then...there is 1099-B because something got sold. In 2017, that W2 amount didn't establish basis for everything? Only for what also got sold in 2017, so there was a 2017 W2 amount (the award) and the 2017 sale. And another round of new release happened in 2021, but you stated the value of the award was not on the W2. That would make me go back to the 2017 W2 to see if that was all of it and only some was sold.

Gross proceeds and cost basis would not have the same value unless it was issued at FMV and immediately sold at that same value. It is more typical for the employees to get this at 85% FMV, so it's strange that proceeds match basis.