Sim's Age Changing Randomly

I'm experiencing a bug where my sim's are randomly changing. It seems to be specifically triggered by them aging to elders. They will change in appearance (back to original hair color, no more wrinkles, body type change) and in age bar back to young adult or adult. It's happened twice so far, both occurrences in the same save though the glitches happened in separate generations of the same household. The most recent time, their age bar showed how many days they had left in their adult life stage, but it was actually showing how many days they had left to live.