First tip: don’t leave your game running in the background. Please close the game completely after your gameplay session to make sure the idle clock starts working. 

The game has multiple saving checkpoints, one happening right before you leave the game. Make sure that you are on the main screen before you leave the game (that means that you shouldn't close the game if a menu window is open; close all the menus and keep the game open for a few seconds in the town you are playing -main levels or weekly events, no problem-).

In order to prevent loss of progress, try to wait some seconds to leave the game after the last upgrades are made. Remember to close it from your background activity, and avoid abrupt game closings.

If this is a recurrent issue for you, check your connection settings before leaving the app. If you play the same game on multiple devices, please don’t play in your secondary option when doing important actions such as playing the event.

*The training of troops in the event won't be affected by the idle limits like the rest of the resources.