After corresponding with C1 about if/when they will provide an update for C1 20 to allow use on my new MacBook Pro, I received a reply that they will not be doing that and that I should update to C1 21 if I want to continue using C1. It does not work on the M1 computers, freezing at the closing of the app.
I have purchased every update going back to V 6 or 7, decided this time to skip a version as I didn't see much of significance in the new version. Now, six months after the new version 21 was launched, it is useless.
I wouldn't expect C1 to provide any new feature updates from v21, just a usability feature. I've been using it in 'light' mode while continuing with Lightroom as primary image processor. I have no intention of 'relying' on a software application which behaves like C1, so bidding farewell to C1. Several other image processing-related apps have handled this smoothly, C1 has not.
Anyone contemplating using C1 should consider that it really is a subscription model you must purchase every time, and at a much greater cost than LR/PS which I see so many complaints about. The reality is that LR/PS is much more consumer-friendly and wallet-friendly than C1.