statusbar icons not changing

[AC Question]

Hi,
I have the problem where it seem apps are not allowed to change/update its statusbar icon.
For example, (and this is not the only app) I run BeWeather, and it has an option to change its default statusbar icon to instead display the temperature.
Every time i try to do such changes, with any app that offers it, nothing happens. Same default app icon stays in the statusbar.
Anyone know what might be the cause?

device: Xiaomi Mi Note
android: 6.01

thanks in advance!
Jay