Lifetime Learning Credit Received Last Year But Not This Year?

Hello!

 

I am a graduate student and have received the Lifetime Learning Credit for as long as I have been filing taxes. I am still a student at the same school, but for some reason, while TurboTax is indicating that I qualify for the Lifetime Learning Credit, it then transitions to "You can't claim an education tax break." None of the reasons it provides for why I might not qualify apply to me. I transitioned from being a Master's student to being a PhD student last year - could that be causing an issue? But I'm not sure why TurboTax would know that. 

 

TL;DR: What would cause me to receive the Lifetime Learning Credit last year but not this year if I'm still a student enrolled at the same school filing under the same status and spending more tuition than I did last year?