Hangouts - no phone found for selected person

[UncleMike]

My son is having issues with group texting, which prompted me to do some testing. I usually use the Messaging app on my Moto X for SMS, but switched to Hangouts for these tests, and typically don't use Hangouts at all otherwise. When I create a new message to my son, and then tap the icon on the left to switch to SMS, it sends an SMS just fine. But if I try to add another recipient to the message, selecting another son (who appears in a square button at the top of a list of contacts), Hangouts tells me "no phone found for selected person." How is Hangouts not able to find a phone (number?) for my other son when he's listed in my contacts with a phone number?

 

[zuben el genub]

You mean Google didn't grab all your contacts?
I don't sync mine. I export them to SIM and VCF files. If the contact isn't synced to your Google account, it won't see it. My contacts say phone only.

 

[UncleMike]

All of my contacts are part of my Google account. Below the larger icons at the top of the list, there's "People you hangout with", followed by "Phone Contacts". If I select a contact from the large icons or "People you hangout with" I get the message "no phone found for selected person", but if I select the same contact listed under "Phone contacts" it works find and add them as a recipient of the SMS.

I also have listed in the large icons, a person I don't know, who contacted me once via Hangouts. This person is not in my contacts at all, and the only way I found the get rid of them is to hide the contact. It's as if Hangouts is keeping its own list of people I've "hung out with" that is separate from my contacts.