Shared One Note not displaying correctly

Question

Hi,

I have created several notebooks in One Note and have successfully shared them with my colleagues. However, I sent a share invitation to someone new within our organization and when they opened it (using the link I sent) the notebook was empty. He doesn't receive an error stating the notebook is empty (as I have seen others report) the notebook is just blank.  

We are both using Microsoft 365 and we both can successfully receive and send other notebooks to people in our organization. These notebooks are hundreds of pages long so we cannot do the workaround that I have seen others suggest where he downloads each page individually.

Also when I look at my notebooks to see who has permission, he is on the list. When he looks at his notebooks and clicks on "shared with me" it shows my notebooks in there. But again once he clicks on that, it opens to a completely blank notebook.

I have sent him an invitation from inside the notebooks using the share option in the top right corner. I also went to File > found the notebook to share > and clicked on "invite people to this notebook" but neither way is working.

Please help.