This is a known issue. Some requests get poorly formatted, and change to party invites. If you restart/refresh your game the good invite will be there.
The second part a witch or transport probably caused the issue. Without a screenshot that is what i have to assume. The first part is probably just the server is behind give it some time or restart your client.
This seems like it was most likely the witch screwing up his job. You gave us enough information to duplicate this 3v3 scenario though, so we can test it. Thank you.