I have a 2008 Mac Pro and am holding out for something with new architecture (as in, USB-C, Thunderbolt 3, etc) before I replace it. Therefore, I am currently stuck on Xcode 8.2.1 and 10.11.6. However, I have the comment problem many have seen before (the change in commenting moving from being native to being a source editor extension and that not being loaded). I have tried all of the tips out there, like "sudo /usr/libexec/xpccachectl", renaming the application, etc, and my console shows that right after it loads it unloads.
While I have been able to get it to work on another hard drive, which just has El Capitan and Xcode 8.2.1, my main hard drive (well, SSD) that I have been carrying forward for 9 years or so, has the xcode extensions unloading on a regular basis (to the point where I can never get the commenting to work). I understand I could probably take a few days to recreate my boot drive from scratch, reinstalling everything one at a time and seeing if any of them cause the conflict, I don't really have the time for that right now nor the inclination.
Has anyone tackled this and found what the conflicts are? Would anyone be willing to assist me by looking at some of my console and log file messages? I would really like to be able to use this machine for another half a year at least, and not being able to comment in Xcode is pretty major....