In case this helps anyone else, I was able to import my 1099-DIV and 1099-B from Morgan Stanley at Work.
After a few weeks, I checked again, and I now see an option for Morgan Stanley at Work as as importing brokerage!
I had to log into my Morgan Stanley at Work account and select the option to share information to Intuit or something like that before I could import the forms.
Hope that helps!
Good luck!
