I have an existing ARKit motion capture app that I recompiled in the new Xcode beta and ran on an iPad Pro (LiDAR model) running iOS 15 beta. I ran it alongside my iPhone 12 Pro running iOS 14.6 and did a video recording of both to see the improvements to motion capture. The recordings are identical which suggests to me that the ARKit 5 improvements were not enabled somehow. Is there something more I need to do? Does the current iOS 15 beta include the ARKit 5 changes?
I tried the same test (iPad Pro 4. Gen, iPadOS 15 Beta2, Xcode 13 Beta 2) with my AR app and the motion capture sample app from Apple. But in the logs I observe errors and the character does not become visible. I wonder how you were able to run your motion capture app and get the character visible. The motion capture improvements were announced in WWDC21 for devices with A14 chips. Maybe they are not enabled for devices with A12 and A13 chips.
I cannot speak to your difficulties. I have a pre-existing app that successfully uses the motion capture with iOS 13 and 14. In my test I ran the same app simultaneously on a device running iOS 15 beta and another running iOS 14.6. I recorded a video of each and compared them. Motion capture works on 13.5, 14, and 15, but the new precision of ARKit 5 is supposed to be limited to A14 chips
Just tested Beta 3, same thing
Just tested Beta 6, same thing