ISO same year exercise and sale not showing expected short-term capital gain

I exercised ISOs this year and then sold the shares as part of the company being acquired (privately). The sale price was greater than my strike price; however, when I enter the exercise and sale in TurboTax (Home & Business), it says there was no gain or loss.

 

To simplify, let's assume I was granted a single  ISO on 8/1/2014 (strike price: $10k), exercised on 11/1/2020, and sold (company acquired) on 12/1/2020 for $50k. Because the company was acquired the same year, the 3921 correctly lists the exercise price as $10k and the FMV on exercise date as $50k. I would expect to incur $40k short-term capital gains for the sale.

 

What I'm doing:

  • Stocks, Mutual Funds, Bonds, Other: Click Update
  • Click Add More Sales
  • Yes, I have a 1099-B and I'll type it in myself
    • Box 1c (date sold): 12/1/2020
    • Box 1b (date acquired): 11/1/2020
    • Box 1d (sale proceeds): 50,000
    • Box 1e (cost basis): 10,000
    • Box B: Short-term, noncovered (since the strike price is not reported on my 1099-B)
  • None of the less common items on the 1099-B apply
  • This is employee stock -> ISO, and I sold shares exercised in 2020
  • Sale information
    • Date sold (box 1c): 12/1/2020
    • Number of shares sold: 1
  • Total proceeds is $50k - Looks right to me!
  • Form 3921
    • Date option granted (box 1): 8/1/2014
    • Date option exercised (box 2): 11/1/2020
    • Exercise price per share (box 3): 10,000
    • FMV - exercise date (box 4): 50,000
    • Number of shares transferred (box 5): 1

The next screen says I have zero gain from the sale.

It says the net sales price was $50k, with $10k being price paid and $40k being compensation income. This all makes sense to me.

It also says that the cost basis was $50k. But that's not right, is it? I get that the FMV was $50k when I exercised, but I only paid $10k. Why aren't I getting taxed on this difference?

 

Thank you for your help!