Choosing a larger education credit or deduction seems incorrect

I have 2 students in college, neither of whom has taken an education credit in the past.

 

For 1 student, TurboTax suggests I play around with education deduction/credit amounts, up to $4000, and doing so ends up saving me about $1K.

 

For the other student, TurboTax doesn't show me the screen.  I played around, and by reducing the amount I say I paid for room and board by $5K, it shows me the screen, and let's me do something similar.  But when I increase the room and board back to the original amount, when I get to where that credit screen was, it says it's no longer beneficial, and it will helpfully reduce the credit to $0, causing my apparent taxes to go up by ~$1K.

 

How can saying I paid less for education cause me to save money?  Probably unrelated, but I did mistakenly withdraw a few $K extra from a 529 for this student.  But if anything, reducing the reported expenses further should only exacerbate that situation, not save me money.  I think there may be something wrong here.  For that matter, TurboTax never let me enter the 1098-Ts (somehow inheriting them from last year but putting $0 in).  I had to manually find the forms and enter the amounts directly, outside of the interview process.  Very disappointing difficulties this year.

 

Any suggestions as to how  I can get TurboTax to allow me to file for the credit?  Or explain what is going on?