I've been working on a survival world recently after not playing for a while. I decided to build a mob farm where mobs fall onto a 2x2 square of half-slabs to prevent mobs from spawning in the collection chamber as well as allow the drops to pass into hoppers underneath that move them to a chest. I have attached quite a few screenshots, but no schematics unfortunately.
It works pretty well, when mobs land I can kill them in a punch or two and their drops get collected in a chest underneath (using the hoppers). Unfortunately, I can't seem to collect the XP orbs that they drop without breaking a couple blocks. This is doable, but it would be nice if I got it working 100%. I have attached pictures below to demonstrate.
Drop area after mobs have been killed before I collect XP:
Drop area after removing slab. The XP has drifted/homed-in so it's right behind the stone brick block:
This was right after I broke the stone block, I was unfortunately not able to grab a screenshot before I collected the XP, that's how close it was:
This is on a server on the most recent version (1.12.? I think). There aren't many plugins so I don't think that would effect this though. I also have placed slabs in the spawn areas so spiders can't spawn.
Does anyone know what the problem here is and if/how I can fix it?
Here is an album that I hope will show how the farm is designed: https://imgur.com/a/XAcQb