In all probability relations between Corbyn and McDonnell soured within weeks of the June 2017 GE, i.e., at about the same time in early July 2017 when the well known windmill in a hurricane, Owen Jones, was calling for JC to resign as Party leader. Given the closeness of Jones/McDonnell, I doubt he'd have made such calls unless they benefited his one time mentor McDonnell. Indeed, Chris Williamson has a large number of bones to pick with McDonnell, who effectively sold his own support base out, Sad.