Plug your phone in and turn off Auto-Lock/Power Saving mode if it’s on. Enter the Troops menu, switch it to Show All. Scroll down through the whole list. Repeat for Weapons, Banners, Pets, etc.
I did that and haven’t had any loading problems on iOS, didn’t have to reinstall either, and I have an iPhone 8 Plus on iOS 11.3. Longest loading screen I got was for the Events tab, and I just played through a whole Pet event with no glitches or battles not loading. Hope that helps.