I had the same issue, and finally downloaded the 8801 form and instructions from irs.gov, and completed the form manually to obtain the value from line 26 to be entered, which was zero in my case.
What I have learned in completing the forms and searching other responses on this site is that having an AMT credit is pretty rare unless you have stock options that are exercised in a different year than the year in which you sell that stock.
The irs instructions stop you at a certain point if the results are zero, and say not to complete or file the 8801 form, so this is perhaps why TurboTax does not have this information to carry over from prior years. However, I think this is a feature that should be included in the software, as all the data to make the calculations are already in there. Normally, I am a big fan of TurboTax, but I believe this is a flaw in an otherwise great program.
It was nearly $700 when I followed the instructions. I had to open a form and enter my State income tax as a negative number in a form and then come back to 2017 taxes with a number and when I did that I picked up a nice little bonus.
But I am confused about it, as I don't know if I should now use the altered version of my 2016 taxes to calculate THIS or should I go back to the return that was submitted to the IRS.
Stuff like this almost makes you start to doubt whether you can do taxes via TT anymore or if it has gotten too complicated.
Of course, congress seems to have simplified it for next year, much to my chagrin as I live in a state with vehicle taxes and such, so I am concerned I will come out behind with the new plan. But we shall see I suppose. Might be worth it to not have this headache each year. LOL