[acerier]

I am an iOS developer, and I too attempted to install OmniFocus for iPhone onto iOS 7 Beta 2. Typing in my Omni Sync password did not sync.

I followed the instructions on this thread: I opened Preferences in OmniFocus 1.1x on the desktop, and opened the Sync preferences view. I selected Show Clients and unregistered the phone I had updated to iOS 7.

I returned to the phone and a new sync worked perfectly.