Rule number one in production. Never, never, EVER upgrade an OS when you rely on your apps to work. Always install a new OS to a separate partition/volume along with your production apps and test until you're certain everything works. In the meantime, you can keep working under the previous OS where you know things function as expected.
This is also normal for Quark. Apple almost always makes last minute changes to the underlying OS before its official release. Because of that, Quark waits until that official release so they only have to test and release an upgrade patch once. Not one a week before, and yet another a couple of weeks later when Apple's last minute changes caused them to have to rewrite and rerelease the update.