Same thing here. Opensprinkler Android app does not load. It just stays there with the Opensprinkler logo and then it goes black and stays like that. I can control my OSPI fine via Chrome on my phone.
Huawei Nexus 6P Android 7 stock.
I tried this on my son’s Motola Nexus 6 Android 7 and it loads fine.
I am a software developer so if you need logs send me a message.