I have been updating the Feedback post (FB18362829) and wanted to update this page as well; Restoring an image of VisionOS 26 resolved the issue, with no changes to code. This implies the issue appears when updating OS versions. I am unclear if the issue is present when updating with Beta versions, or if non-beta updates are also affected.

Updating to visionOS Beta 4 and Xcode Beta 4 allows the build to run as expected! When first updating the Vision Pro to Vision OS 26 Beta 4, builds initially failed. However, a few minutes later a 2nd prompt to finish the Beta 4 installation appeared. I'm not sure why the second prompt appeared or what happened the first time I had to remove the Vision Pro for the update, however it appears that the combination of visionOS 26 Beta 4 and Xcode 26.0 Beta 4 resolves the build issue.

I am using Version 26.0 beta 2 (17A5241o). All other projects tested worked as expected with this version of Xcode Beta. I will remove it completely, install Beta 4 and try again. Thank you!

I have submitted a report on the same day, code: FB19189965. It says 'Unable to diagnose with current information.' What additional information would you need?