I've created a watch with a horizontal series layer of type "Day of the month number" and Gradiant Radial shader to make the outside dates fade out.
Every night at midnight, the shader on the series disappears. It is fixed if I change to another watch face and change back (from the device itself) or re-send the watch from the app to the device.
I'm using a Huawei watch. Here is the watch configuration: https://drive.google.com/open?id=0B0m1BV1DgKgLWmZmckdaWTlRclE