It seems there’s an issue opening documents. I’m working on a fix.
The opening documents issue is intermittent, and it smells like an Apple bug. After some time, it seems to fix itself.
There was another issue of bad screen coordinates when sculpting (possibly also an Apple bug, having to do with frequently switching the rendering resolution, as Sculptura does to maintain performance), which I was able to work around by calculating coordinates a different way.
It now seems to work well on my end, but we’ll need to do some beta testing, and then submit to Apple for review.