My brothers and I started a L.A.N world in 1.13 and were playing just fine for quite a while. When we updated the world and started playing on 1.14 suddenly all the mob spawns stopped.
No wither skeletons or blazes in nether fortresses, no slimes in our slime farm, no hostile or passive mobs seem to be spawning (except illagers and merchants as seen below).
We have had travelling merchants spawn and despawn just fine, we also ran into an illager patrol and thought they were the problem, but after killing them and rebooting the world we have had no success.
Upon rebooting the server we occasionally get one or two spawns, but then we end up with nothing very shortly afterwards.
Is anybody else having this issue, and if so have you fixed it?
If you need more info I'll try my best to provide whats asked.
My boyfriend and I were playing 1.14 on LAN. Our render distances were both pretty normal (around 10 I'd say), there was minimal lag (besides chunks loading when moving quickly) yet NO mobs were spawning (rather, virtually none). It could be a RAM related problem, though I've read that turning your render distance up really high then back down to around 16 will yield normal spawn rates.