Exporting transparent movies in Keynote doesn't work anymore...

Hi,

I have several times used the function to export a slide as a transparent movie (to overlay in Final Cut) - but for no reason that doesn't work anymore.

I get a result with a black background now.

I do the right things - set the slide background to "No fill", and export as Prores 4222 with transparent background - but the background still it ends up being black. I have tried everything from just a shape on the slide to animated graphs - it's the same.

I use MacOS Catalina v10.15.1 and Keynote v9.2 (6520).

As stated - I have done this numerous tikes before - but now it doesn't work.

Any tips to why?

Best regards

Jens