Elder guardians not in ocean monument and mob grinder not working in beta

I have the beta 1.2.13.5, I have a survival world and I tried to fight the elder guardians and they was not there, I thought it was because I'm clearing it out so I went to a different one and still no elder guardians. Also I made a mob grinder in a creative flat world with mob spawn cages and they worked. But in my survival world they aren't working I tried putting it 150 blocks above ground level still didn't work I also tried it on ground level and block height limit and it's still not working