Could you provide what ProjectKorra version you're using and what Spigot version you're using aswell as how out of date you are (by using /versions on your server you'll the number of versions behind you are). You're likely out of date.
You are 256 version(s) behind 23.05 08:37:22 [Server] INFO Checking version, please wait... 23.05 08:37:22 [Server] INFO This server is running CraftBukkit version git-Spigot-518206a-a5b9c7b (MC: 1.13.2) (Implementing API version 1.13.2-R0.1-SNAPSHOT)
You can keep minecraft version 1.13.2. Spigot releases updates almost daily and it includes bug fixes and such. The reason you could be having these issues may be because of how out of date you are and you don't have any of those bug fixes. I recommend you extract the latest Spigot 1.13.2 jar from BuildTools or you transition your server to Paper (it's a lot easier to obtain a Paper jar file).