Confused as to why I got a PTC refund from my 1095-A form last year and not this year.

Last year I had an AGI that was around 150% of the federal poverty line. I had a 1095-A form last year where I put the correct info in columns A and B, and put 0 in column C because I did not pay anything in advance. I got a huge refund from the 1095-A form, However, this year, my AGI is less than it was last year and I have the same situation with the 1095-A form where I had info for columns A and B, but 0 for C. However, I did not get a refund for the 1095-A form this year. Why is this the case and what, if anything, am I doing wrong? Thanks