All armor stands suddenly gone (Minecraft 1.15)?

I play on my Aternos server on version 1.15.

I put up figures with armor racks. With this page: https://haselkern.github.io/Minecraft-ArmorStand/

All of the armor stands in the world were suddenly gone today. What can I do?

That happens to me all the time

Then what did you do?

Rebuilt