Hi Caxton
I had this a few times and asked MOz help and they said:
"that type of message is typically crops up when there is an issue with the level of permissions associated with the GA login info that was used to connect it. So, I would recommend making sure that it is being re-authorized with the most authoritative set of admin credentials for that GA account; ideally, the original creator of the Google Analytics account."
They also said to watch the number of GA accounts/profiles since has a token limit and once exceeded can cause connection issues. So say your accessing a a clients design agencies GA account to import your clients data into Moz, if the agency has lots of clients all with their own GA profiles in their accounts then that can cause you to exceed token limit and break the connections.
However i can always reconnect/reauthorise the connection (although very annoying that i have to every time i view a campaign), wheras sounds like you cant reconnect so prob best to email help@moz if i were you.
Hope this helps a bit !
All Best
Dan