ISO - Employer Acquired & cashed out my vested ISO

My publicly traded employer was acquired in October, 2024. My vested ISO shares were granted in 2020 & 2023; and all were exercised & sold for cash on 10/4/24 as part of the company acquistion. The 'gain' was approx. $12k.

I can not find it as part of my wages or any other section on my W-2.  The only tax documents I received were the Form 3921s which showed the no of shares, exercised price, and FMV. I did not receive a 1099-B or any other tax document and no one available from prior employer to ask.  

Do I need to report the ISO $12k on my taxes? Should I have received another tax document? 

Thank you.