The bug
When you use the /fill
command to create a room, or use a structure block to load a structure, the lighting will not properly update inside of the structure.
To reproduce
Go into the sky
/fill ~ ~ ~ ~15 ~15 ~15 minecraft:white_concrete hollow
Enter the concrete cube
→ ❌ Occasionally the room will be partially bright inside. If you open theF3
screen you can see that the client and server light values do not match.
Linked issues
is duplicated by
Attachments
Comments

Cannot reproduce in 1.16-rc1 using the command you put in the descripition after trying a dozen times on multiple test worlds.