Updated steps:
If any Orion window is open, quit it.
Open a new Orion window.
Go to any site that plays media (YouTube, for example)
Start playing media
Open a new tab
Return to the tab playing media
Close tab playing media
Try it with this? That seems to guarantee that it occurs for me on a clean profile on Orion 0.99.130.2-beta, for me.
Clip: