If you are using TurboTax Online, try importing using a different browser.
If you use the Brave browser, you have to turn off the Brave Shields.
See the following TurboTax Help articles for potential fixes:
See this TurboTax support FAQ for importing a Form 1099 - https://ttlc.intuit.com/turbotax-support/en-us/help-article/import-export-data-files/import-1099s/L2hPcduMb_US_en_US?uid=lu1ltvxz
I need the answer to this question as well.