I'll keep this short and sweet. I have a BlockEntity which has an inventory, and a custom renderer class. The renderer displays an item/items from that inventory in the world. The problem is, that when the world is loaded, it doesn't render the items until the player has interacted with the block.

I don't know if this means the BlockEntity doesn't load its contents until interaction (such as with chests when they generate loot, since I was using the Chest code as a bit of a guide), or that the Renderer doesn't see the items because they aren't synced with the client until I interact with the block.

If anyone can shed some light on this, that'd be greatly appreciated. Thanks

This is relevant to you since the data is synced to the client only when you tell it to be. Otherwise, it will remain forever empty on the client.

Ah, thank you, that's perfect. Implementing getUpdatePacket(), onDataPacket(), getUpdateTag() and handleUpdateTag() fixed the problem.