In my survival world I started a new base in the middle of nowhere, far away from any villages. Over the course of building stuff I „collected" several zombievillagers: lured them into my well lit-up underground (so lightning is no issue) base, „stored" them in seperate 2x2x2 chambers, threw something for them to hold to them (though not all of them wanted something) and nametagged all of them. They were present for a couple days. As soon as I built chambers for my trading hall I wanted to bring them over there just to discover that ALL OF THEM were gone. I sometimes switch from normal to hard mode, but never to peaceful, and I didnt switch difficulty the whole time they where present. Noticed their absence today, pretty sure two days ago they were all fine. No roaming dogs or irongolems anywhere. They also have not been in boats or minecarts, and their chambers were next to each other on the same level, so no chunk border issues.