"So at the end the gains/loss is eventually calculated based on the corrected value and not the actual cost basis. Right? "
Correctl, (more or less).
Your actual cost basis would be $10; that's set as the stock's FMV at vesting.
The "Cost Basis" reported on the 1099-B is $0: you had no "out of pocket" cost.
The Adjusted Cost basis should be $10.
You'll report a $1 ST gain per share.
