We recently updated two Mac's in our studio, and both are set up exactly the same. We have an issue on one Mac, where is we collect a document for output it locks up right at the end - and after a restart, the file can be opened but cannot be saved. We've tried duplicating the file and renaming it, saving it to a different location, moving the file to a new folder and deleting the preferences, yet the only way we can resolve it is to copy it across to the other Mac which saves it with no issues. Once copied back across the file can be saved again.
Both 27" iMacs running El Capitan 10.11.6, with Quark 12.2.1