I've done this for the past decade or so, but seem to be having an issue today.
What am I doing wrong, and what should I be doing instead?
Did you check in the Income section, under Your 2024 Income Summary > Import Summary to see if your data imported?
Some users have reported that they needed to enable 'third party access' in their brokerage account to import. Others have stated that their usual Sign In to their brokerage account needed to be a Document ID instead (from PDF download of 1099 data).
Be sure you temporarily disable all anti-virus software (including modem).
Let us know if you can't resolve your issue after trying some of these options, and we'll try to help.
Here's how to Contact TurboTax Support for more help.