Jackson Perkins

Here's a video showing me doing it https://www.youtube.com/watch?v=oO1QtzRIVhM&feature=youtu.be
Here's the world I used in the video https://drive.google.com/file/d/1fRf3A5ovIIVdki0zw4gTIZameoOeM7IS/view?usp=sharing 

Here is the link to the world
https://drive.google.com/file/d/1pAP_Uz6mBGtJuXFw20SmmQnDtO9e_ppD/view?usp=sharing

I can confirm this happening to me on a server. I had just moved some villagers to my house (they were in minecarts in a safe location, no mobs), then I went to get rooms ready. I went back up to get them, they had seemingly despawned, all 7 of them.

1.15.2