Additional Information:
Trying to make Brave my daily driver and honestly this is a bit of a bummer. Didn’t work on Mojave and doesn’t work on Catalina.
Hello, @dustinlocke. It sucks that PWAs are not cooperating for you.
I tried installing and running the Twitter PWA in my Nightly install (1.5.27 Chromium: 79.0.3945.117 (Official Build) nightly (64-bit) on macOS Version 10.14.6 (Build 18G1012)) and downloaded the main release (1.2.42 Chromium: 79.0.3945.117 (Official Build) (64-bit)) to try that, too. In both cases, I was able to quit Brave, launch the Twitter PWA, and browse Twitter successfully without changing settings.
I’ve not made the leap to 64-bit-only, yet, so my OS lags yours. That said, a few things might possibly cause issues:
Do you have any extensions installed?
Is your browser part of a Sync chain with an iOS device?
Are you running AV software, security software, VPN, or the like?
Have you tried clearing cookies and relaunching Brave?
I would also consider creating a new browsing profile (Main menu --> Create new profile) and trying to create a PWA from this fresh profile.
Also, to confirm, @dustinlocke – absolutely no PWAs work in Brave? For example, this site (community.brave.com) should allow you to install as a PWA – you get the same results when launching this site’s PWA as you do with others you’ve tried?