I have a prototype that was updated and published using XD 28 and it now errors before displaying anything.
The error in Chrome dev tools gives me this stack trace, (originating from share.js):
RuntimeError: memory access out of bounds
at Ii.ri.update (player-vector.js:1:145530)
at t.value (share.js:218:302847)
I've removed the absolute URL paths here, but hopefully this is enough to get the conversation started.
Before updating to XD 28, the prototype worked as expected. I only added a couple elements to the updated prototype before publishing, so I doubt I've reached some kind of memory limit (this is also a relatively simple prototype, consisting of only 2 artboards, vector objects and text). That said, I can fix the issue by removing an artboard from the prototype flow.