"I'm not seeing the the next screen after you enter the details of the sale, which is supposed to say 'Let us know if any of these situations apply to this sale.' Any ideas what might be going on here?"
Are you entering individual sales ("One by one") or summary entries ("Sales section totals")? You don't get the "Let us know" screen for summary entries.
"I need to enter an adjustment with code O to include additional fees not captured on my 1099-B."
Shouldn't the fees be entered as sales expenses, code E, rather than code O? That's what code E is for. According to the "Learn more" help in TurboTax, sales expenses would include such things as wire transfer fees, phone or fax fees, and express delivery fees. Entering code E is much easier in TurboTax. And according to the Form 8949 instructions, you're only supposed to use code O if no other code applies. (I also suspect that code E is less likely to be questioned by the IRS.)
There's no way to enter adjustment code O in the Step-by-Step interview. It can only be entered in forms mode. You have to enter it on the Capital Gain (Loss) Adjustments Worksheet for the sale. Find the sale on the Capital Asset Sales Worksheet. Click on any text or numeric field for the sale (not a drop-down list or check box). For example, click on the Property Description. Then click the little magnifying glass that appears to the left. This will QuickZoom to the existing Capital Gain (Loss) Adjustments Worksheet for the sale if there is one, or it will prompt you to create one.
On the Capital Gain (Loss) Adjustments Worksheet, in Part III, scroll down to the "Other adjustments" box at the top of page 2. Check the box for "Other adjustments," and enter the fees as a negative amount. This will enter code O in column (f) on Form 8949, with the amount that you entered in column (g).
