Why (sometimes) I can't change avatar/contact image of a contact?
I reopened this question as suggested by comment.
There is a problem with changing the image/avatar of a contact.
If you try to change the avatar/image of a contact, edit/crop it and then swipe left to "Accept" the changes, sometimes nothing happens. The image of the contact stays empty. After some "research" (thanks to the answer below), I can confirm that this happens for all choosen images without correct suffix (in my case no suffix at all).
After renaming the file (i.e. with correct suffix - e.g. ".jpg") the contact image can be assigned.
But as you can see the image in Gallery and the image is presented as valid choice, the question is, why is the contact image only assigned with a correct suffix?