Collected and tamed two each of the llama colors, then bred them to get four each. Then gave them chests and carpets.
Randomly, some number of the llamas will just be missing from their enclosure when we come back to play the game and we have to breed again (sometimes even having to go find a new llama of a certain color).
Last night I played and purposely stayed close to the enclosure. No problem. I went into the Nether for awhile and came back... all the llamas were there. I explored a new map for a bit and came home, all the llamas were there.
I closed the game when I was sitting near the llama cage. 10 hours later, I reloaded the Realm and 2 of the white llamas, 1 brown llama and 1 yellow llama are missing from the enclosure.