I selected form8949.com, which worked well at reasonable cost. The app produces a properly formatted 8949 PDF from the 1099B CSV. The summaries match the Fidelity 1099B PDF, so calcs are presumably correct. IRS has a procedure to mail these PDF to support TT electronic filing, so everything should tie together. I provided TT the summary data so overall return can complete. It is still case that TT not supporting a claimed feature, and hopefully they fix, but this workaround enables completed filing for 2023. form8949.com takes ~20 seconds to process the data and deliver the PDF forms, so it doesn't seem like TT should have difficulty doing same. Its no more difficult than an Excel spreadsheet, with IRS specified output format.
