Keynote & Pages don't open files after update

Hi there,

I recently updated to MacOS Big Sur and the newest iWork, but now both have troubles opening new files. E.g., when trying to open a keynote file, created on Tuesday with just the previous version of Keynote, I get only the message of "downloading" that doesn't seem to go anywhere, regardless of the time I wait.

Also, when adding pictures to a new Keynote presentation (yes, I can open a new one), the whole Keynote freezes and crashes.

Is this a known problem and how could I fix it?

Thanks,

Anja