Message+ app does not download text messages. I only get text message notifications
Enthusiast - Level 1

As in title. The actual phone on the verizon network is a Pantech perception that can barely qualify as a smartphone. I have the message+ app on my iPhone (iOS 12) and that's where the problem is. Text messages don't show up on my iPhone's message+ app anymore all I get are notifications that I've gotten a text. But when I enter the message+ app the text messages aren't there. I can send messages through message+ but not see any texts I'm receiving. I can see the texts on the Pantech. I didn't used to have this problem until this weekend so I'm led to believe a message+ software update goofed. How can I see my texts again?