New version failure to download/launch MacOS

Latest Zwift update automatically started to download but froze at about 98% complete. Hitting “Let’s go” didn’t progress past launcher.

Deleted all Zwift files, restarted MacBook Pro and did fresh download and install of Zwift launcher. Now auto update is frozen at about 55%.

Weirdly, Finder does not report Zwift as ‘not responding’ in the Force Quit dialog (it did on my first attempt).

Everything was working fine yesterday…

2017 Intel MacBook Pro running MacOS Monterey 12.1 Beta.

Help!