I can't share much code because it's proprietary, but this is a bug that's been haunting me for awhile. We have SceneKit geometry added to the ARKit face node and displayed inside an ARSCNView. It works perfectly almost all of the time, but about 1 in 100 times, nothing shows up at all. The ARSession is running, and none of the parent nodes are set to hidden. Further, when I look at Debug Memory Graph function in Xcode, the geometry appears to be entirely visible there (and doesn't seem to be set to hidden). I can see all the nodes attached to the face node perfectly within the ARSCNView of the memory graph, but on the screen, nothing shows up. This has been an issue for multiple iOS versions, so it didn't just appear with a recent update.
Has anybody run into a similar problem, or does anybody have any ideas to look into? Is it an apple bug, or is there a timing issue I might not be aware of? It's been really hard to debug because of how infrequent it is, and I haven't found it discussed on any other forums (but point me in the right direction if there is a previous discussion). Thanks!