Kroger natural pb is my go to brand! In fact I just picked up 10 jars this morning.
We've been using it for years.
When you open it the first time you REALLY have to stir and stir and stir. I spend a good 5 minutes getting all the hard stuff off the bottom and mixed in to the liquid on top. If you don't thoroughly mix it at this point you get real dry stuff at the bottom. Which even that is not a waste. I just throw it in baked goods when that happens.
BUT the best method is to do a real deep mix up upon first opening, longer than you think you should need to... Then each time we use it we do a quick stir.
If yours is in the fridge and still liquidy it definitely is fairly solid on the bottom. Get a knife and dig in to that bottom chunk until you can get it stirred around well.
I don't refrigerate ours. I find it gets too hard plus with our family it never lasts long enough to worry about going bad. But I know a lot of people do.