In general the LoadPostData
is the standard place to load the post-back data for a control and since the selected indices are stored in the client-state, this is where they are applied to the control. As for the statement that the tabs are hidden, in general when the selected indexes are being applied first all tabs are unselected and then only the ones which hierarchical indexes correspond to one from the client state are being selected.
In order to help you troubleshoot the experienced problem, my suggestion is to open a support ticket and provide a runnable sample.
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