I would just like to share that I ran into this exact same issue for my 2023 return (Turbotax Online 2023-2024). It's still impossible to change the values in Form 8801, whether by questionnaire or by manual override.
Furthermore, I tried getting a refund twice, once over the phone and once with the online form, and was rejected both times, on the grounds that Online cannot be returned.
(Of course, if I hadn't paid for Online I wouldn't have been able to preview the incorrect Form 8801 in the first place!)
I ended up filing a dispute with my credit card company. I encourage everyone running into this issue to do the same, instead of wasting their time with a refund claim. Intuit simply does not let you get a refund for the Online version, even if you can demonstrate that it gets your taxes wrong.
