What @sdrohan said is correct! OmniFocus 3 for iOS introduces a variety of new features, such as tagging, new repeat options, and a revamped perspective editor that offers a range of powerful new filtering options for custom perspectives. These features will become available on the Mac platform when OmniFocus 3 for Mac is released later this year in September.
In the interim, custom perspectives that have been created using the new OmniFocus 3 perspective editor will not appear when synced with OmniFocus 2 for Mac. When editing that perspective on your iOS device, there is an option at the bottom of the editor to “Downgrade Perspective”. Doing so will make the perspective sync-compatible with OmniFocus 2 on your Mac, but will also eliminate any aspects of that perspective that utilized newer filtering options added in OmniFocus 3.
The amount the perspective would change during the downgrading process would depend on the unique characteristics of the perspective, and which filtering options you’ve selected.
To summarize, any perspectives you wish to have access to on your Mac will need to be downgraded for the time being, until you upgrade to OmniFocus 3 for Mac after it’s released later this year. Any other perspectives that you don’t need on your Mac—or that require new perspective filtering options—can remain on the new OmniFocus 3 perspective format.