I have a problem, when i edit the page and click on, "insert webpart or app part". I cant see any webparts or app parts in the category list to the left. Its empty, only thing i see is the category, Apps.
What can it be?, I'm in the owner group aswell.
It's a permission issue. Add user to "Designer" group then they will be able to see full options. I just encountered the exact same issue.
Please go to Site Settings > Web Designer Galleries > Web parts then Library tab > Library Settings > Permissions for this gallery and Check permissions.
You need read permission to see the Web parts.
On the SPOnline site that I administer "Owners" don't have page edit permission. It's possible that you need a higher permission level to do anything but make basic changes to your own page.
