Logged onto realms on 1.17 for the first time and many mobs have disappeared.

Logged onto our realm on 1.17 for the first time (world was made in early January 2021). Me and another player were not by our base when we logged on, but when we returned dozens of our mobs had disappeared. Several dogs and parrots, and dozens of villagers were gone. I restarted Minecraft but they did not reappear. 

I will include images of before and after (of the places that there are pictures of).