Sims Birthday

I keep noticing that during my gameplay, my sim's birthday keeps getting pushed back. It would show up as happening on the 3rd day during winter, and then I would check again and it would move further away. My sim basically never ages up because of this bug. 

I don't know if its a CC/Mod issue because I've never had this issue up until now. 

I've checked to see if the auto aging system was turned off and it was not. I've tried giving my sim a birthday cake but the option to blow out the candles to age them up, is not even available. I have to constantly go into CAS to age my sim up.

This has happened in two of my households.