This is normal. Patches generally invalidate save games when too much changes in the game engine.

Did you update Entrenchment between when you saved and when you tried to load? That will also break the saves.

It turns out when I was playing entrenchment, I loaded from Impulse. Then when I wanted to play the next day, I loaded from the game directly. Turns out I didnt notice the "Play Entrenchment" menu option and was using "Single Player" menu option, which loads the original game and not the expansion pack Entrenchment