From experimentation, I've discovered that the bug occurs when trying to allocate more RAM than is currently available. Check your JVM arguments and change -Xmx<number>G to a value that your computer is able to allocate.
Getting same issue. Bug occurs with 2 differently named banners that are lime green.
I think that it is the player data, I had to delete all of it to fix my server.
Jared Wood
From experimentation, I've discovered that the bug occurs when trying to allocate more RAM than is currently available. Check your JVM arguments and change -Xmx<number>G to a value that your computer is able to allocate.