Dear All, ,
While we are trying to access Manage Live Mobile Access which is part of Nintex Forms Management getting issue.
Method not found: 'Void Nintex.Live.SharePoint.Services.OnlineProxySettings.SetProxy(System.ServiceModel.ClientBase`1<!!0>)'.
I would suggest verify NINTEX Live settings in SharePoint central administration...
You should take a look at Nintex Forms 2013 - Product Update Process second part : "Establish a connection to NINTEX live"