I have kept the app up to date and it happened on my iPhone 6s as well as my new XS.
It is getting so bad I avoid using the mobile app for important calls. I am curious if anyone else is having this trouble.
I think my next troubleshooting step is to use the old mobile app for a while to see if it shows the same problem or not. If it does not then feel like the issue is with the newer Glip mobile app itself.