I just purchased the other treats from Buy mode to learn their recipes. They seem to be working fine. I think I might have found the cause of the issue: the fridge will only recognize fruit/veg purchased at the grocery store in town to use in the Friendly Treat recipe. I had been attempting to create the treat before using fruit/veg grown in my Sim's garden. But when I purchased a few produce items at the grocery store in town, I'm now able to create the treat.
However, I have way more than the requisite ingredients in my fridge; the game just isn't recognizing them for some reason (attaching pictures to show). It seems to only recognize the items bought from the store, not home grown produce.
Currently don't have a localthumbcache file to delete!
