Simple Sandboxed Solution won't reactivate if scoped to Web from Solutions Gallery

Hi All,

I've got a bizarre problem which is really confusing me and I'm hoping somebody could help please?

I've created a very simple Sandboxed solution in VS2012 - empty SharePoint Project with one empty element and in that element's XML, I have the following within the <Elements/> tags :

  <CustomAction Id="Steve.AltLogin"
                GroupId="PersonalActions"
                Location="Microsoft.SharePoint.StandardMenu"
                Sequence="100"
                Title="Sign in as a Different User"
                Description="Login with a different account.">
    <UrlAction Url="javascript:window.navigate(SP.Utilities.Utility.getLayoutsPageUrl('CloseConnection.aspx?loginasanotheruser=true&amp;Source={SiteUrl}'));"/>
  </CustomAction>

If I right-click and deploy, it gets uploaded to the solution gallery and activates, and immediately I have the new custom action in my menu under my name to enable me to login as another user (I know I could have modified welcome.ascx to achieve the same but wanted something that wouldn't break in the event of a platform upgrade).

Now ... if I go to the solution gallery and deactivate it, the menu option disappears as expected.

If I reactivate from the solution gallery, the menu DOES NOT reappear.  Similarly, if I upload the .wsp as a virgin solution and activate, it doesn't function and the only way it will work (seemingly) - is a direct deploy from Visual Studio.

I noted that the feature is scoped to Web and I'm deploying to my top level site in the site collection.

If I change the scope to "Site" - everything works as expected and I can activate / deactivate / reactivate to my heart's content with the expected results.  Similarly - I can upload the .wsp to another farm via the solution gallery and the custom menu action appears.

Am I missing something here or is there a "bug" with a feature scoped to "Web" not working via the solutions gallery?

Thanks

Steve