Villagers vanishing at night

I've seen a few complaints about entities disappearing but I haven't found anything that goes into much detail, I'm hosting a minecraft server on my computer and building a village with a few of my friends but at random villagers will disappear at night as if they have died. I have lit up the village and even played on peaceful while building some of it but they just keep vanishing, I have yet to find any pattern to the disappearances but my best guess would be that they are getting unloaded when i go home while they try to get to their bed and for some reason they aren't persistent. I know that they are no longer in world as I use a command to make all villagers say something in chat and the ones that I cant find do not respond.