It might be worth pointing out that even the default "YourVisual" that appears as a placeholder in DevTools, for me at least, fails to render at all on iOS when exported and loaded . I'd be inclined to think that no custom visuals were rendering at all, however I am still seeing chiclet slicers as mentioned before.
I have no interest in using YourVisual generally, but it seems like a particularly good test subject given it's a case of Microsoft's own sample failing to run on its own platform. It's also a very quick and easy test. It would be useful if others could try it to eliminate the possibility that this is anything account specific.