The lack of crew contact is the most telling piece, with an engine failure I would think that at some point a mayday would be issued especially when carrying extra crew members. The fact Iran is refusing access to the flight recorders and a statement was made within an hour stating engine failure as the cause are all red flags. Tensions were extremely high just after the missed launch by Iran and it is not outside the realms of possibility that everyone would have been a bit trigger happy towards any perceived threats. I hope it is not the case but the evidence seems to be suggesting something more complicated that a poor
y controlled engine failure.