Don't know about the DMGC 5 but the chat feature is working properly. I was facing problems with the Duo app but did 'Force Stop' and 'Clear storage' for the app, now it's working perfectly... You can try that for the Message app, hope that works.This ROM is almost perfect. I just found some issues.
1. Android Messages Chat (RCS) feature is stuck at "Trying to verify your number". Tried some troubleshooting but same issue persists.
2. DMGC 5 by thedise doesn't work. It always crash upon launching the app.
Hope these can be fixed soon. Thanks!