Picture #1 ... nice baitball, but no fish seen

Picture #2 & #3 ... baitball is deep for a reason (temp, oxygen levels, barometric pressure), no real discernible school of fish seen - possible scattered singles even deeper, but well away from baitball (possibly already fed, or may be reacting to weather conditions)

Picture #4 ... even larger baitballs, but still no obvious fish markings. Even deeper in the water column

I wouldn't have fished these Shad schools, myself ... but, would have gone looking for other baitballs with larger fish markings that were in closer proximity to them.
One thing to understand, too, is that in warm water ... fish don't see as well. Likely why crankbaits being trolled around during this period are producing better than small jigs or minnows, but that's just a hypothesis of my own. That being said ... if I were to find a baitball with a school of fish close by, and I wanted to hover over them & fish --- I'd likely use something like a Kastmaster, or large blade bait like a Silver Buddy, and rip jig it. Dropping it to the bottom & ripping it up a couple of feet & then letting it flutter back down on semi-taught line would mimic a Shad in distress or dying, create a disturbance that was noticeable above the sound of the baitball, and give the impression of an easy meal.

Crappie won't charge into a ball of bait like a White Bass, Hybrid Striper, Black Bass, etc ... but, will pick off stragglers or the wounded/dying. You have to make your bait appear to be that "easy meal", while at the same time make it stand out from the baitball (in sight/sound).

... cp