I believe that the reply thread is not fully accurate. You can certainly write off the stock as a capital loss. However, there is section 1244 of the IRS code that basically lets you write off a loss against income rather than a capital loss. The appropriate form to file is the 4797. I'm trying to use it for the first time right now and that is what brought me to this page. I see that you entered your message for 2023, so this may be too late to help you, but perhaps it could help someone else in the future.
I was going to enter the data into TT's form view, but figured out (with the help of some out-of-date but useful comments from the community) how to get TT to do the work. Basically, treat the loss as an investment loss. Lie to TT about having a 1099-B for the company and at the end of the dialog, there's a box to check indicating that it's a 1244 stock.
If you're looking for the thing to do for a successful exit, investigate section 1202.
Good luck with your investments.
*** I am not a tax pro, so don't believe anything that I've said here.
