Photos missing from iCloud Contacts on Nexus 4

I'm using SmoothSync for Cloud Contacts to sync my iCloud contacts to my Nexus 4 and 7 devices. Normally it works like a dream, but yesterday I woke up to find that all the profile photos were missing from all my iCloud contacts in the "People" app for no reason I could figure out. The fix was simple: delete the account and recreate it, but I'm listing the steps here because they're not really all that obvious.

1. Open "Settings."
2. Scroll down to "Accounts" and click on "SmoothSync for Cloud Contacts."
3. Click on the account.
4. Then click on the three-dot Option menu indicator and select "Remove account."
5. Open the "SmoothSync for Cloud Contacts" app and re-enter your account information.

I had a concurrent issue with my Google+ profile picture not showing up on my Nexus 4. Strangely everything was fine on the Nexus 7, so no idea how to account for the difference.