2017 desktop version unable to download fully 1099 B transcations from Schwab, probably more than 2000 transactions. How to handle this?

Although I cannot help you with TurboTax Desktop not being able to download fully your 1099-B transactions from Schwab I can give you an alternative that is better than manually entering each transaction. The alternative would be to enter summary totals for each asset sale category. It will require you to mail a copy of your Form 1099-B along with Form 8453 (which TurboTax will generate). To do this please follow the steps below: 

• In TurboTax, click the search icon and search for "1099-B" or "1099B" (lower-case also works) and then select the "Jump to" link in the search results.
• Click + Add an Account (if the account you were trying to download is showing, delete it first)
• Answer Yes to "Did you get a 1099-B or a brokerage statement for these sales?"
• Click on "I'll type it in myself"
• Select your Bank or brokerage and click Continue
• On the page with "Tell us about your ... 1099-B" click the button "I'll enter a summary for each sales category"
• Enter your Investment Sale information and repeat to you have entered for each category.

After entering all your category summaries,  Look for "To finish reporting these sales, follow the mailing instructions" and click on the link for these instructions:

this sucks