Hi @ all,
once more, I've found strange behavior of an UWP/C# application I developed.
The image within button content suddenly (rarely, occasionaly, in one of 1000 application runs) changes to the another one from solution assets. 
Normal (coded) look of button: 
There's no code within whole app affecting the button content. The button content is set just once in XAML: 
Of course, I've rechecked multiple times the code related to this button. At runtime, only visibility property gets changed from time to time: 
How can I prevent such occasional issue?