Message + won't open on my MacBook Pro
I've been using Message+ successfully forever to text with my Verizon account on my MacBook Pro, but now tthe app won't open on my MacBook_just a grey window with no content. I've trashed the app and reinstalled but same thing. Won't open. All I see is a grey window. Any guidance on how to trouble this would be appreciated. Verizon techs are of no help. Supposedly there is no other app other than Message + to text on my laptop with my Verizon account. Please advise. thank you.
MacBook Pro 13", macOS 10.13