v4.09beta in the Play Store
Attention Moto360 users:
This is completely unrelated to Bubble Clouds, but I added a workaround in the app instead of creating a standalone application:

The 5.1.1 OS update introduced a strange, and annoying bug which was not corrected in the latest (1.3) update either. Hence my decision to do something about it:

If you have Auto-brightness enabled, and your battery goes below 15% the screen doesn’t light up in the dark. You have to disable auto-brightness for the screen to turn on.  Of course you cannot do that with the screen already blank, except if you:
►go to a better lit area, where the backlight will turn on again
►or triple-press the physical button to enable Sunlight mode (temporary max brightness)

When you enable the new option — which only shows up for Moto360 users – other watches don’t have this bug or don’t have auto-brightness setting, because they don’t have light sensors — Bubble Cloud will take care of this setting for you. When battery goes below 16% it will switch to manual brightness. That’s all to it.

Background:
The blank screen is caused by a brightness setting, that is so low that the backlight doesn’t even turn on. Normally the backlight is controlled by the light level reading: the higher the ambient light level is the brighter the screen needs to be set. My suspicion is that in battery saving they use a slightly altered function to convert measured light levels into screen brightness, which has this bug. When it’s too low (light level = 0) it sets the screen brightness to 0 too…