After updating my Omnisync password and subsequently updating to the current build of OF ver2, I lost my OF Reminders calendar. It didn’t show up in OF or in the Calendar App. Calendar did report a sync error. Ahhh, I thought, I need to re-authenticate with my new password. So I did (in Calendars App) and it worked… Once. After the next re-sync period, same thing – no calendar. Re-enter the password and it’s back. I fixed this by blowing away all of the Keychain Access passwords for Omnigroup, refreshing the Calendars and re-entering the new Omnisync password. My expectation that the keychain password would be updated is incorrect. I had about 9 different Omnigroup entries in my keychain – your mileage may vary and perhaps the Keychain system got confused. If you experience this after a sync password change, it’s likely NOT an Omnifocus bug.
During this test period, always make sure that “Publish due items as calendar alarms” item in the notifications preferences has not been reset to Off if you want to see your alarms. That flipped on me a few builds ago but I’m re-checking Preference settings in every build now. So far so good; the product is getting better with every build.