I finally found the Google Calendar Sync Troubleshooter.
Here's the step that fixed it for me. Several layers deep in the Troubleshooter, but finally resolved the issue!
We recommend proceeding with these steps only if the above steps don't resolve the issue.
Open your device’s Settings.
Select Applications, then All.
Select Calendar Storage.
Select Clear data. Answer OK when prompted.
Turn Calendar sync off and on in Settings > Accounts > Google > [your affected account], or from within the app using Menu > Refresh on newer devices. If you receive an error message upon opening the Calendar app, close and re-open it to re-activate sync.