We are continuing to work on this issue. We do not yet know exactly what is causing the crash, but we are getting closer. We believe this is related to support the “improved support” for extended-range pixel formats and wide-gamut color spaces that are found on the newer iMac 5k displays. It is possible this is something that Apple needs to fix, but we may be able to work around it (if we can reproduce it) now that we can reproduce it on our new(ish) iMac 5k.
@philw Can I please get a copy of your calibrated color profile that is causing the crash? We are working get our hands on a 5k iMac where this crash is occurring, but we will need a color profile that is causing the crash to reproduce it (the default does not seem to crash). I believe you can export these profiles using the ColorSync utility.
In the meantime, for users that are experiencing the crash (likely on a 5k iMac), please change your color profile (System Preferences > Display > Color) to the Standard iMac Apple RGB profile for the time being.
It is worth noting that Apple has just released a public beta of macOS Sierra 10.12.1. It is possible this issue is fixed in that release and we would greatly appreciate anyone who is experiencing this issue and can reliable reproduce it, to test this out on the 10.12.1 beta.
It’s great to have so much capable help chasing down this issue.
Y’all are awesome,
-Dan