GridView sorting in UserControl inside UpdatePanel
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I did find similar questions, but no conclusive answer.

If I put a GridView inside an UpdatePanel, everything works fine.
However, if I have it inside a UserControl: (Like: <UpdatePanel><UserControl><GridView></..>),
sorting by clicking the headers on the GridView doesn't work anymore (nothing happens).

I can of course handle sorting manually (maintaining a ViewState manually), but is that really the only way?
Is GridView inside UserControls inside UpdatePanels simply not supported?