Wandering Trader baby Llamas vanish when growing up

I'm breeding Wandering Trader Llamas, i'm afk for a while with 4-6 baby Llamas, when i check back if they're grown up they vanished. (about 10 minutes every so often)

I breed the grown up tamed llamas again, i put white carpet on the adults one, anyway if i breed them again i get babies like it should but then i play a bit (caving) or afk and when i get back the babies are gone, i play on peaceful so no mobs that could have slaughtered them. 

Ways to reproduce:

• random peaceful world
• wait for wandering trader to spawn
• kill wandering trader 
• keep llamas
• tame llamas by riding them
• put white carpet in carpet slot of wandering trader llama
• breed llamas with haybales
• get baby
• wait
• sometimes they seem to stay sometimes they're gone