Sooo... I Have a new version of your mod and a lil issue with it. When i go into dungeons everything is ok, i spawn normally without problems but when my friends try to go into dungeon they spawn under bedrock withou ability to move/jump/teleport/respawn above it. Any ideas?
More information please. Is it a LAN world? What coordinates are they spawning at? Is FlatBedrock enabled? Did you update the mod between you going into it and your friends going into it? In the meantime, I suggest having someone with operator powers teleport them up to where you are.