No Preview/Edit possible: page never loaded

[peculiarPrince]

Stuck on loading screen.

Could click "next" and download the recording (which did not have a thumbnail preview).
Tried again after 30 minutes, could preview and edit a new recording (did not reload page manually, but possible that page automatically refreshed when using another app on tablet then coming back to Firefox).
Downloaded file can be played on tablet (even if previewing was unavailable in Studio).

[LukasKalbertodt]

With #1069 everything changed a lot, so this might have squashed the bug. Or not. But in either case, I don't think we ever managed to reproduce that, so I don't think keeping this issue open serves a purpose.