Prior to the update I had a skeleton spawner that swept spawned skeletons to a precipice that then damaged them via the fall to half a heart and has pistons that then pushed them into a lazy river that transported them approx 36 meters to a processing area where I would then slaughter them for copious amounts of arrows, bones, gold armor and experience. 

After this update, the skeletons spawn and are pushed towards the processing area but it appears the skeletons are despawning somehow. I find a few of them in the collection area but the hundred or so that I'd have waiting for my sword are not there. 

This is not a good change. This is not a welcome change. This negates lots of engineering work. I'm really not happy with this.

I can provide worlds and anything else needed to examine what's going on. Just ask.