I am using the Google Calendar app to sync all my calendars since I find it smarter than the standard iOS calendar app. However, I am unable to get my Google Calendar app to sync in the background on my iPhone. The app starts syncing to my calendars as soon as I open it, but it does not update events in the background if I don't start it.
I have my Gmail account set up correctly in the "Accounts" section, with "push" turned on and "every 30 minutes" manual sync if push is not available.
Background app refresh is enabled.