Unable to tame ocelots

In my Minecraft Realms server, I am unable to tame an ocelot and what happens instead is the ocelot gaining hearts above their body, but no collar or ability to sit the cat. I've tried this with 4 cats all yielding the same result. I also don't have any animal tamed. I have tried reloading the world on an old back up save and F3 + T. This yielded no results. Please help with any suggestion, thanks.