I received the following error screen when tried to use invite code to the all chat.
Turning Ingress off(close) and on again, then checking Niantic chat allowed me to have the group as 'joined'.
Also, the 'retry' screen stays. Leaving the 'groups' tab from Niantic chat and returning to it keeps the 'retry' screen. There is no reset.
This happened to me with the first group I joined by invite code as well. Did not happen with the second.
I had the same thing happen. I did not close or exit the app, just hit 'retry' 3 or 4 times, after which it worked.