When Creating an Office 365 SharePoint site, you might want to turn on custom Scripting.
With Custom Scripts turned off you might experience some weird behavior like:
- Content Types and Site Columns Galleries are not showing up in the Site Actions menu.
- When Mapping a SharePoint Library to a local drive, you might get Access denied errors when trying to upload files.
- CEWP and Script editor web part might be missing from the Web parts list when editing a page.
References: