FS#1615 - Mobs not spawning while under a glass roof.
I’m not sure if this is a bug, but it doesn’t make sense on why it would be happening. I placed a glass roof over my natural shadow aether mob grinder and they aren’t spawning. The area isn’t region ed so there is not reason why the mobs shouldn’t spawn while under some glass.
If you want to test it out just go to /warp Shadow Aether Mob Grinder and toggle the bridges on the roof.