I'm not sure if it will help, but you could try deleting the account and signing back in. Start by saving any photo stream photos that you want to keep to your camera roll (unless already there) by opening your my photo stream album, tapping Select, tapping the photos, tap the share icon (box with upward facing arrow), then tapping Save to Camera Roll. Then go to Settings>iCloud, scroll down and tap Delete Account, provide your password and choose Delete from My iDevice when prompted, then after a few seconds sign back in. (This deletes the account and your iCloud data from your device, but not from iCloud. Your data will download to your device again when you sign back in.
Since you don't know which device is causing the problem, or if its both of your devices, you may need to do this on both your iPad and your phone.