Error "This import was unsuccessful" when importing 1099s from a Charles Schwab account with many transactions

Using TurboTax Premier 2025 Desktop on a Mac, I am able to import 1099s on 3 of my 4 accounts, but the 4th account (which has by far the most transactions) will not import. While there are many transactions on this one account in 2025, the number of transactions is still much lower than I had in prior years when data imported with no issues.  This is the message I get from TurboTax:  "This import was unsuccessful.  We recommend you check your internet connection and try again.  If we still can't get your info, don't worry.  We'll help you enter it manually so you can keep working on your taxes." This importing is the primary reason I buy TurboTax, and I will buy other software and TurboTax will lose a 25+ year customer, before I enter manually. How do I get HELP so TurboTax will fix their issue and enable me to import all my 1099s?