This has been happening for every species and in every reserve, sometimes animals will simply ignore callers, whether they are traveling or in a need zone.
I think this has to do with animals that have been spooked previously, but as you can see in the video, they are already calm again. Something that helps is to make them go alert again and then calling, as for some reason this will attract them again.
This bug really affects players that want to walk around the map instead of relying on need zones, making a playstyle unviable, so please, address it as soon as possible.