Setting rights for CustomAction. Problem with sandboxed or language?

Question

I've got a CustomAction which contains a button. Only users with high level permissions should be able to see this button, so I tried setting the property Rights ="ManageWeb" on the CustomAction. When I deploy this to my farm solution with the english language pack, the rights settings works fine - only users with ManageWeb rights can see the button. However when I deploy the same solution to my office365 site with a swedish language pack, All users can see the button. I've also tried using RequireSiteAdministrator = "TRUE" instead. Didn't work either - everyone still saw the button.

Any idea what the problem could be? I've googled around and doesn't seem like the Right property should be language specific. So any idea what the issue could be

This is basically the custom action: (Removed some commands and other stuff from)

<CustomAction Id="SiteRequestCommand"
                   Location="CommandUI.Ribbon"
                   RegistrationType="List"
                   RegistrationId="{$ListId:Lists;}"
                   Sequence="30"
                   Rights ="ManageWeb"
                    >

..

    <CommandUIExtension>
      <CommandUIDefinitions>
        <CommandUIDefinition Location="Ribbon.ListForm.Edit.Commit.Controls._children">
          <Button Id="ApproveSiteRequestButton"
                       Command="Approve"
                       Image32by32="/_layouts/images/workflowstatus_completed.png"
                       LabelText="Approve"
                       TemplateAlias="o2"
                       Sequence="30"
                        />
        </CommandUIDefinition>

      </CommandUIDefinitions>
    </CommandUIExtension>
  </CustomAction>