NOTE: Indigo 2022.1 has solved this issue.
Just as we were publishing our blog post concerning Indigo, Python, and macOS, we got some disturbing news. Unfortunately, Apple is continuing its new trend to break backwards compatibility in macOS Monterey dot releases. For the macOS 12.1 problem, we were able to quickly release a fix. With macOS 12.3, however, the fix is huge. Note: macOS 12.3 is now available and it will break Indigo.
As we discuss in the blog post referenced above, we've been planning on distributing Python 3 with our first major release of this year, Indigo 2022.1, understanding that Apple never makes big breaking changes in dot releases (saving those for major releases like 11->12 and 12->13) and that we had until the fall release of macOS 13 to complete migration. Apple has been warning that they were no longer going to include any Python release and so we made our plans according to our understanding of the timeline.
Sadly, as has become somewhat the norm with Apple recently, they are changing their typical release patterns. We have been and are continuing on doing the work necessary to transition to our own Python 3 release. This work will likely not be ready before macOS 12.3 ships which means that Indigo 2021.2 and earlier will not work on 12.3.
We have hopes that the Apple developer and enterprise customer bases can raise this issue loudly enough with Apple to get them to change their minds. We don't have a lot of hope that it will work, so we’ll be doing everything we can to have Indigo Python 3 compatible as soon as possible. However, the accelerated timeline will likely require Indigo users to hold off updating their Indigo Server Macs until we've completed that work and most 3rd party plugins have been updated.