Hey lefvaid, I think I know your problem, because the title has this Latvian ā included. What You can do is rename your video/audio file to "Sudden Lights - Aija" (with a normal "a" at the end) and also change the name in the txt file under #MP3 #COVER #BACKGROUND and #VIDEO. Then it should work
In #TITLE you don't have to change it, UltraStar is able to read those letters in-game, only the txt file has some trouble with that.