@gruva Thanks. I had considered that as well and spent a good amount of time today lighting the cave systems I could find in the area, killing every mob I found. I even built a second larger farm in a different chunk. I still don't have any slimes spawning. I updated my bug description and uploaded an updated version of my world to reflect the lite caves and larger farm location.
Add 1.2.10 to the affected versions.... The change log claimed they fixed this but I still have zero slimes spawning. This is a game breaking bug that needs to be fixed ASAP. I can't build anything I want to build without sticky pistons. I'll be forced to cancel my realm subscription if this isn't fixed before the renewal in 9 days.