I use a custom MapRenderer for my plugin. This plugin draws some things onto the map, and as long as you are in the same world, everything works fine. But as soon as you switch the world, the canvas doesn't draw anything onto the map - after that it doesn't work for any world. The render() method is still called, though. The Renderer is contextual - this means, this problem only appears for the person who switches the world, but not for everyone.

After quitting and joining on the server, it works again flawlessly. (Maybe a problem with the RenderData of the specific player?)