Arelith

I've been noticing a lot of my rolls have been off in battle when I'm casting. I "failed" numerous spell rolls even though the rolls themselves were successful.

You can see plainly that the creature's rolls were lower than the DC, and therefore a failure, but they were labeled as successful.

It looks like they rolled 20, which is auto-success regardless of if they beat the DC or not.

Above poster is correct.

1 is auto fail save, 20 is auto success. Same rule applies to most rolls I can think of.