Should I change that and test again? If so how do I change that?
As far as I know its a clean install of mac OS, clean java install, and no server mods or anything. I haven't touched java or lowered the setting at all.
I don't think it matters if it runs fine on any other world does it?
This is not a bug, the handling for entities has changed. For whatever reason, although not quiet pinpointed by me yet, the new entity handling system works. I have proven my work by making a spawner as by such methods/commands with mcedit filters, then I put a NEW fallingsand entity in my world. I then copied the NBT data from that sand into the spawner and it works! Give me a few minutes and the new handling will be found! NOTE TO MODS: This is NOT a bug, simply a new system. Please remove this from confirmed status
EDIT: Problem was in the original command syntax is "Block:"minecraft.dirt"" as opposed to "block:"minecraft.dirt"
EDIT #2: Also the block will not spawn without a required player range, ie "RequiredPlayerRange:10" should be on the end of that command