LG G4 :: Cannot See All Contacts When Trying To Create Group

I tried to create groups on the native phone app on my LG G4. Although it allows me to create a new group, it only shows a single contact as an option for any new group. I have 1000+ contacts on the device, and the native Contacts app has them (when I click the Contacts tab, there they all are).

I was on an hour-long chat with t-mobile who kept telling me the steps for creating a group, which I know. Their final advice: hard reset. I just got the damn phone, so I'd like to avoid the stress of configuring 100+ apps, folders, contacts, etc.

FYI, I have one Exchange email account and a few gmail accounts, if that has any relevance. I just migrated from the Samsung Galaxy S5 on Verizon and I relied on groups a good amount.