This shit happened to my PS4 also.. I did not uninstall the application, though.
In my case, I shutdown and relaunch the application, but this did not work.
Netflix for one episode, and tried again, but still did not work.
I tried to erase the local file from the save data. (I do not recommend this.. I thought I crashed my account information. It was ok in the end, but I did not think this worked.)
>it fails and leave you on a loading screen saying "could not join the mission" with an "accept" button and I just left it on THAT screen for a few minutes.
I think this worked for me in the end.