The most common reason why you cannot see your King’s Banner is that your VIP Banner is currently active. Once you reach enough VIP points, the VIP Banner is automatically activated, and the game cannot display both banners at the same time.
To restore your King’s Banner, you need to disable the VIP Banner.
For Mobile Version (Empire: Four Kingdoms)
Go to Settings.
Select Options.
Open the Symbol tab (Wrench icon).
Uncheck “Show VIP Banner.”
For Goodgame Empire (browser version)
Go to Settings.
Open Options.
Deactivate the VIP Banner.
Once the VIP Banner is disabled, your King’s Banner will be visible again.