Changing this offset doesn’t do anything, at least not visually. I placed a PrintString in there to check the Z-value, it never fires. But I’m not a pro, maybe PrintString isn’t intended to fire here …
The more I tested, the more things confused me. So I created a new 5.1.1. project, empty world, just lighting and landscape given. Migrated the birds folder into that new project. Did a basic setup: Added a standard box as a post, removed colission mesh and to be safe deactivated colission. Added NavMeshVolume, put a perch target on top of the post, ground target on the landscape, sky targets, well, in the sky. Threw 4 crows in and that’s it. No params changed. The result is still the same. Crows that come to sit on the post hover some cm above it. Crows landing on the landscape do whatever they want: One of them looks ok, another one’s offset is negative at the same time:
