I've been exploring Minecraft in the versions 1.14-1.14.3, and others have experienced similar effects on their villagers.  They disappear.  I'm commonly traveling in and out of chunk distances and villagers disappear gradually.  One missing, then two until I'm left with an empty village.  This has happened over and over again, and I tested it with a secure box underground with the light level no less than 8.  They disappear.  Other people in the bug reports have noticed as well and the issues are all resolved, but the villagers and other mobs continue to vanish.