I'm not sure, but maybe there is a limit per day ?
To avoid people taking 200 pills in a row ?
Pets that loot at 5m are pretty much useless anyway.
The point of an auto-loot is to be able to grind without having to worry about the looting action.
But most mobs, even in melee, are considered to be 5m away from your avatar, so if they are 5.01m away, which happens a lot, many of them will not get looted.
So you have to keep checking to make sure you don't miss any, sometimes turn around to get closer to the mob, etc.. Very annoying.
I got bored leveling up a 5m auto-loot pet, and when I finally got to use it, I stop using it after 2 days when I realised it was useless. (who can imagine that argonaut arms are 6m long?)
Maybe you should think about getting a real auto-loot pet...
https://www.planetcalypsoforum.com/forum/index.php?threads/leprechaun-gold-32m-autoloot-pet.283179