The problem is it is not spawning you within 20 blocks, it ends up being in the hundreds. Like 200 blocks away. Here is an example of the difference I experienced. Spawn point set to -159 70 479, final resting spot -87 73 364. Alot more than a few blocks. When I created a fresh server world with default server properties, it works just fine. Only with this setup does it fail. The only thing I can think is the spawn protection setting. I have it set to 150 instead of 10. But I cant imagine that would effect were people spawn. Or at least it should not.