Library settings wont save my changes in Sharepoint Online.

Hi,

Library settings wont save my changes in Sharepoint Online. I am an Sahrepoint admin, and I am creating a new communication site. 

When I try to create a column, or add from existing column site, it wont save my changes. Whenever i try to save, it says "Sorry, you dont have access to site" even though I have access. Iam site admin/owner. Any ideas why ?