I ended up giving up on TurboTax Online and using the local version (specifically the Mac version). That had no trouble importing my 220 page long 1099, although it did take a *very* long time. The 1099 had a great many very small stock sales listed. In the end this produced more than 2800 pages of Capital Gain (Loss) adjustment worksheets. Clearly the online version of TurboTax wasn't up to the task.
