[Macos-users] Keynote 11 problems with images on dropbox

dear Mac users,

do you know the following problem with Keynote 11 (vs 6.5.2):

when I open an existing presentation I get the warning: "some images are missing, because they are removed from the document" (or something similar; I use the Dutch version of Keynote). Indeed the images are missing and appear as empty boxes with a question mark.

I stored the keynote file on DropBox - so my impression is that DropBox changed something in the permissions of the images. When the presentation is stored as “package” I see the images in the Data folder of the package.

Any solution how to get these images back in the presentation?

thanks! - Stan