Cannot get Multi Camera control working!

G'day all, 
I'm hoping someone can save me from losing my mind . . . I CANNOT get MultiCamera control to work! 

Action Cams (I bought 4 based on being told MultiCam control was possible) 

FDR-X3000
HDR-AS50
HDR-AS50
HDR-AS50

Phone: iPhone 6s

iOS: 10.2.1

PlayMemories App Version: 5.8

Method: I followed these instructions carefully about 10 times! 

Results:
I can easily control one camera at a time with the PlayMemories App when in normal WiFi mode . . . My phone sees the camera in wifi settings fairly easily (very temperamental though, my home wifi constantly kicks the ActionCam off).

As soon as I change to MultiCam mode my phone cannot see any of the cameras in WiFi settings. 

I cannot see any external connections connecting to my Personal Hotspot as per the instructions. 

Can anyone here successfully operate multiple ActionCams from their phone? 

Any help would be greatly appreciated! 

I am going to post this in the Action Cam section as well - I'm not sure which aspect is the problem (the cams or the app).

Thanks in advance.