data synchronization – Some Google contacts not syncing to iPhone

On my iPhone, my Google account is the only one that is set to sync contacts. I seem to have a small number of contacts in my Google account that won’t sync to my iPhone, and I can’t figure out why. They are actual contacts, not “other contacts.” I could just delete and recreate them in Google and hope that does it, but there could well be others that I haven’t noticed yet (I have a lot of contacts) so I’d like to find a systematic solution. Any ideas?