Does Illustrator have full access to your photos?
Is it just that one photo or all photos?
Can you import from other locations, e.g. your Crative Cloud folder?
thx Monika, its ok now, it was just one photo who was giving trouble.
It does not work again. It does work when importing from cloud documents, but not from my photos on the iPad.
I get it now, there was no more space on my iPad. I fixed that and now it is ok.