Keynote not saving, exporting or adding photos

Hi guys,

just recently, my Keynote (11.0.1) running on MBP 13" 2020, OSX 10.15.7 started behaving really strange.

Issue 1: Cannot save any keynote

Very often, after saving an unfinished work, even a brand new keynote, I get this error message: "The document “Untitled” could not be saved as “Untitled.key”. You don’t have permission." As per the other forums, I tried deleting recent files, tried switching on/off the iWork autosaving feature, tried copying the whole deck into a new keynote, nothing worked. Tried repairing permissions, saving under different names, repairing access rights on my whole computer including all the enclosed folders. Starts to get really frustrating when, randomly, the Keynote decides not to let me save my work.

Issue 2: Cannot add the photos

Every time now, after drag/dropping any jpeg/png into keynote, I get this error message: "The image couldn't be inserted." It does this while using 'Insert > Choose..' as well as with drag & drop. Have to open the file in Photoshop, select all, copy and paste it in Keynote. this way it works.

Issue 3: Randomly refuses to export keynote into pdf

Every now and then, my keynote (however this issue appears in Numbers, too) cannot be exported into pdf. After the progress bar runs to the end, I get the message saying "The document could not be autosaved. Your most recent changes might be lost." If I send the keynote to someone else, they are perfectly able to export and save.

Again, this is a very unlucky combination as I am unable to use both Keynote and Numbers in even a super basic way.

Thanks