[CLIENT] [MAC] Mission, champion Collection info, Store and Loot fail to load

Firstly, I've followed all advice on the FAQ for debugging all of this. All of the required ports etc are open, my DNS is set to 8.8.8.8 & 8.8.4.4, all done. I've run the HexTechRepair tool multiple times and even reinstalled from scratch a couple of times.

I've been having this issue in varying degrees for some time. The missions page is intermittent, it rarely contains any content. Collection shows all the champ icons but every one of them is greyed out; strangely the one's I've received a chest for still have gold borders. If I restart my machine it will fix the Lobby and the news not being available, but nothing else.

Other info: When I exit the client after it's failed it will normally leave a process hidden in the background (ps waux | grep [lL]eague). With this process running the client will refuse to restart.

Router firewall is active but required ports are permitted.

macOS High Sierra 10.13.6 (17G65) 2.3 GHz Intel Core i7 Intel Iris Pro 1536 MB

Dev instinct: The way it's occasionally able to connect and tries for some time to load content (e.g. store) before failing suggests there's an issue with the response. If it was an issue with my firewall then the requests would fail every time.