In the latest version of Clash of Clans, we made a pretty big change to how the shields that you can buy from the shop work. We introduced a cooldown for each seperate shield, meaning that if you buy a 24 hour shield now, you have to wait 5 days until you can buy the same shield again.
The reason for this change is high level matchmaking. What we've noticed is that some players purchase the shield after each attack, which makes them untouchable to other people's attacks. The matchmaking and ranking system we use works best when everyone who attacks once will also be attacked once. This currently works pretty well for lower level players, but the higher level players are having hard time finding matches because of their fellow high level players are always shielded.
The shield's original purpose was to offer player a chance to take breaks from the game due to real life things such as vacations and still remain competitive when they return to the game. We still want to offer this chance to our players, so the best way to fix the matchmaking was to introduce cooldowns on shields.
Do not panic! We expect the high level players' trophies to fluctuate quite a bit during the coming weeks. If you lose trophies because of this change, don't worry, others will face the same challenges too. After the dust settles, we expect the amount of trophies to be a better indication of both player's attacking skills and also their ability to plan effective defenses for their village (whereas now it's been mostly focused on attacks). Even if you prefer offensive gameply, this is still a good change for you as well, as you should see a lot more targets to choose from!
The effects of this change are not instant as they only work after the current shields run out. It should take a couple of weeks for things to stabilize, so hurry up and build those defences!