Design Manager: Edit Page Layouts : Sorry, you don't have access.
Unable to edit page layouts under Design Manager in Sharepoint site even if user is the owner with full control access. Tried same steps to multiple tenant and we found same issue.
Set-SPOSite -Identity "https://sitename.sharepoint.com" -DenyAddAndCustomizePages $false
Custom Script are all set to
-Allow users to run custom script on personal sites
-Allow users to run custom script on self-service created sites
User friendly option, I think.
Kikimo Mekuto commented
I also need this functionality.