Thank you for contacting us.
From the provided information it is not completely clear what is your scenario, but we succeeded to reproduce such error when using a static view model. Could you please try to replace this code:
AvailableUsers = null;
SelectedUser = null;
AvailableUsers = e.Result;
foreach (var user in e.Result)
And let us know if this works fine. If not, we will need some more information about your scenario: could you please send us a sample project that replicates the navigation logic and the view model bindings from your app.
I look forward to your reply.
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