Agent Andrew said:
Hello! This is not a bug. The game goes to a sleeping mode if a player stays inactive within several minutes. It was made to prevent overloading of the server: the game client (app in your browser) constantly exchanges the data with the server and in the sleeping mode this exchange temporary stops. At the same time, the game server continues processing of all the actions related to the player's account (movement of troops, production of troops and so on).
I know all that - you have missed the point
It is a bug
Why is there NO WARNING in full screen mode?
Please fix full screen mode
To reproduce this bug, log into the game, engage full screen mode, spend some resources then wait 4 minutes snd 4 seconds
The resource bar will freeze, but no other warning is given that the game has hibernated
.... or you could always spend some money upgrading your servers so they don't overload every 4 minutes