I succeed one time in uploading a (music)tune to the Community media. All my next tunes failed to appear after uploading, due tot a very 'misty' red coloured message: 'this field cannot be left empty' . But what field had been left empty...? And what had to be filled in?? No idea.
Problem seems to be solved...my profile settings in the rigth left corner(...) spontaneously changed to 'USA' . As soon as I changed it to 'Dutch', uploading was possible again. Question closed for now 😀