I was having the same problem but after much aggravation, this finally worked for me. I kept deleting and recreating new app-specific passwords in Wealthfront until I got one that worked. Not only is it extremely aggravating that you can't cut and paste but also that you can't see the 32 character password that you are typing. Although it appears that Turbotax is only letting you type in 28 characters, it is in fact letting you type in 32. I figured ithis out when I hit the backspace through the entered password and noticed that it was taking 32 characters even though it appeared to stop after 28. I really think that the reason this wasn't working is because the initial app-generated passwords I was using contained characters that were easy to misinterpret (ex. 0 vs O, and uppercase I vs lowercase l) and that I could not see what I was typing so the possibility of typos is high.
Turbotax needs to enable the copy and paste function or at a minimum let the user see what they are typing.
