Same issue here. Tried reboot, safe mode, uninstall/reinstall. Nothing worked.
On android, go to google play store, click the 3 bars in upper left go to my apps and games, click message plus.
On the next screen click uninstall and it will ask if you want to uninstall all updates for the message plus app. Say yes and it will work fine.
All message threads will be intact and your message + app will be the original stock version, but it will work
Thank you, this fixed my LG V20. Removes all updates and sets the app back to the default settings, but didn't lose any messages. All good for me after an hour of frustration trying other things that didn't work.