@Greymagic27 It seems like turning off the internet makes you be able to access the launcher, albeit on demo mode.
I got an update for the launcher as well, but the glitch wasn't fixed, albeit it's good to see progress.
I'm on Mac OS 10.11.6 and it has been happening for a few days now. I basically tried everything I could to fix it but wasn't able to fix it.
I hope it gets fixed soon.
This is also a problem for me. I'm on Mac OS 10.11.6 El Capitan. Can't play on 1.18 but it works just fine on 1.17 and 1.17.1.