Problems with 'invalid contacts' using Verizon Message Plus

[sizwizz]

I just got a Samsung S5, and was going to try using the Message Plus feature for texting. When I select a contact, it appears correctly, EXCEPT all of the contacts have (M) after it. Because of this, I get a message that it's an invalid contact. When I use the Messenger app, I don't have this problem. It displays normally. Any ideas on how I can fix this? I am on the Verizon network through Straight Talk.