Hi mr-dang,
Thanks for feedback.
To test this issue, I create an app with Compass.Heading and Acceleration functions. Then I run the app on the devices I have (I don’t have Windows Phone (Lumia 950) on my side, so I am not able to test on this device).
On Surface, it seems that I get the same result with you.
In Edit mode, it works fine while in Preview mode, looks like it is a bit slower than in Edit mode.
The PowerApps version on my Surface is 2.0.610.
On iPad, the app is working as good as on Surface Edit mode, all the values can be returned as expected.
I also test this on iPhone 6S, the app also works fine.
The app version on both iPad and iPhone is 2.0.611, and iOS version is 10.2.1.
On Web browser, it doesn’t work, I assume it should be a default behavior.
If convenience, please check if you have given Location access for PowerApps on iPad. If you are still getting this issue, please feel free reply.
Best regards,
Mabel Mao
