I have been researching, but haven't been able to find anything in the settings that allows this. Contact management: LG G5
It may not be a feature on the newer device, but you can try contacting LG directly, although I assume it would be in their instruction sources.
I find this same issue on the stock Messaging app... the only solution I have found is to start up the Contacts app first and then all of a sudden, everything populates properly.
I have switched to the new Google Messaging app and it does not seem to be a problem.
It should have had a pop up asking for contacts permission. You may have denied that permission.
Go to settings
Go to the messaging app
Then make sure it is turned on.
tidbits answer is the correct answer. I reset the app permissions and all resolved.