Black screen when viewing camera on phone app

I'm having issues viewing my camera on my phone app. I'm currently viewing it fine in the online control panel on my PC (so upload speeds on the network/issue with camera are ruled out) but every time I try to open it on my phone all I see is a black screen. I've tried arming/disarming, deleting the app, resetting my phone etc but nothing.

In the cameras area I can see that the preview is working correctly but as soon as I tap on View Live I can't see anything.

Any suggestions?

Thanks