This worked for me...go to "show topic list"(upper right side of TT) scroll down to 529 plan in the state tax area and click on the box. It took me to a dialog box where I could enter the info.
The box may be called different things in different states, but 529 should be indicated as a topic.
I didn't know this last year (in 2017) and missed out on the deduction then. TT needs to address this problem!
I hope it works for you!
