why do you need to import a large transaction file tho? 1099s can all be manually input at summary level unless you have a lot of sales adjustments on 1099-B and want to file 8949 to avoid mailing in a statement.
I just dont want to type in and make mistakes. Is there an upload option anywhere hidden?
You can upload a PDF of stock transactions in TurboTax Online.
In TurboTax Desktop, here's How to Enter a Summary in Lieu of Individual Transactions.
However, if your import is timing out, there are several things you can try:
Here's more info on Unable to Import.