did you get any response? I have a friend who put a 24hrs shield and he also lost him after a few hours ... he is 100% sure it was on, especially as it was just before our first kvk so he did check properly ... he losts millions of troops he had prepared for the kvk and many ressources and plarium doesn't want to do anything because he doesn't have the print screen of the first attack (he has been attacked more than 200 times ...)
after that he also had trouble with 8hrs shields ... sometimes when he clicks, the 1000 gold is taken but the shield is not on and he has to click again and loose another 1000 gold ... it is extremely annoying ...
we are looking for other players having the same issue as plarium says there is no bug ...