This has been an issue I'm noticing with many others running spigot when ever restarting the server most of all mobs and entities are disappearing when starting back up after stopping the server. Mobs like villagers, tamed wolves, tamed horses, most of all friendly mobs have been disappearing even name tagged mobs. Entities like item frames and boats would disappear. I created a forum thread post about the issue and many others have been experiencing the issue.

https://www.spigotmc.org/threads/1-14-spigot-mobs-entities-despawning-after-server-restarts.371523/#post-3398060

I don't know why mobs/entities are not staying and are randomly disappearing after every server restart or crash but this is a major issue if it is happening to many others. When not restarting the server all mobs/entities stay until if I do a restart or if there's a crash.

None of these issues with mobs/entities disappearing never happened in 1.13.2

Same problem on my server running 1.14 built Yesterday. This is not just him having this problem.

Check out the spigot forums at: https://www.spigotmc.org/threads/1-14-spigot-mobs-entities-despawning-after-server-restarts.371523/#post-3398112

Check it out on the minecraft forums at: https://www.minecraftforum.net/forums/minecraft-java-edition/recent-updates-and-snapshots/2959174-villagers-disappearing-from-farms-bug-1-14

Check it out as an official bug report at: https://bugs.mojang.com/browse/MC-150170

Problem happening on regular/vanilla minecraft also. This is not just a 1 person problem. Its persistant over 50+ cases since 1.14 was released. Somebody messed up the entity coding.

Just a heads up its best to report an issue when you are using the latest version of Spigot/Craftbukkit

""You are 30 CraftBukkit and 2 Spigot Version(s) behind""