Turbo Tax put out a large program update tonight, and the problem is fixed for me now.
First, as an experiment I had tried many other financial institutions randomly. While many put up a screen that shows the future date that documents will be ready, more than half presented a login screen. There was no other institution where TurboTax was behaving as it has been for Fidelity.
I tried one other thing - at the forms level, I deleted any 1099 forms that Turbo Tax had imported from last year.
Then I received and installed the update, and it worked. So I don't know if my deleting those forms made a difference, but I think probably not. I think the program update fixed it.
