Just got my DSC-RX100M2 today (October 8, 2017).
Checked on-line and it has the lastest available firmware... no update was required.
Downloaded PlayMemories mobile today (also October 8, 2017). Says it's version 6.0.0.
Tried it from my iPhone 7 (ios v 11.0.2) and iPad Pro (ios v 11.1)
Got the same result on both:
1) Successfully logged in via WiFi
2) Got a "Controlling with smartphone... you cannot directly control this device" message on the camera
3) Get a quick flash of a camera control screen and a viewfinder image from the camera, then the app closes (on both iPad and iPhone).
Have followed the sequence indicated on line (first let camera go to wifi mode, then connect to camera, then launch PlayMemories) and have reloaded app.
Would greatly appreciate help.
Thanks,
Keith