It appears that this issue has been going on for some time.
My old Ally Bank accounts continue to update however, if I want to add a new Ally account, I am receiving an error code. For me, this happened in August 2023 - however, since this was a holding account, I did not need to review the transactions monthly.
Now, I just added another account and because it is used frequently, I need those updates. I contacted Quicken support and shared my screen with them. They watched me try to add the new account and said there was indeed a problem.
As I mentioned - this is really strange because the old Ally accounts will update without any problems, however, Quicken will not allow you to add any new Ally accounts. By the way, I also added another account with a different bank - and that came across and was updated without any problems.
In my opinion, quicken cost quite a bit and now we all have to buy a new subscription each year. Not sure I want to continue if they cannot support us and fix this issue.