Append option grayed out

I’m trying to append a modified unity build to an existing Xcode project. When I go to build though, the append option is grayed out.

Per the dialog warning that pops up, I’ve double checked that the Xcode project uses the same version of unity and has the same device targets. I’ve also tried updating the bundle version as suggested elsewhere on this site.

Since the app contains a lot of custom programming outside of unity, I cannot rebuild the project.

Any Ideas?

Found the answer here. You must build to the project root rather than a sub folder or folder outside of the project: Unity Issue Tracker - [Personal] The Append feature is always disabled if building to any folder that is not the project root