Go SMS Pro not sending MMS photo messages

[AC Question]

A couple months ago I started having sporadic problems sending photos via MMS in Go SMS Pro and recently it has become nearly impossible, I continually get an error that the photo/message cannot be sent. When it occasionally works, it appears to keep "sending" even after the recipient received it. I can still send via the Go MMS version but the people I send to find this method cumbersome and annoying vs. directly sending photos.

Any help would be appreciated.