I believe I have hit the same issue. I've just started trying to contact turbotax support. I'll reply with what I hear back and would love to hear from others that have hit the issue.
It is not clear to me exactly what turbotax is putting in line 2, but it definitely seems wrong and, in my case, is resulting in the wrong AMT credit carry forward.
When I manually fill out a form 8801 fixing this line, I see the numbers I expect. I'm not sure how this helps me with using turbotax though.
Looking forward to hearing what we should do to resolve this.
