Snrub, You are right. BG's and Crappies are both like that.
Sometimes they will stop hitting a certain lure or bait. Someone might think there are none left in that spot. But change colors or sizes or styles of lures and they start hitting again.
And spawning BGs will turn off and move deeper after cold fronts or heavy rain. They usually only move a little deeper but sometimes they still will not hit anything even live bait.
They can get finicky and you have to figure them out.