Cyrillic characters not displayed in song title on main window

Cyrillic characters are correctly displayed in the playlist, but they are not rendered properly in the main window's song title area. Each Cyrillic character appears as a blank/whitespace character instead.

Reproduce the issue by opening a song with Cyrillic characters and comparing the main window's song title area with the playlist, where the characters render correctly. Trace the main-window title rendering from that comparison; done means every Cyrillic character is visibly rendered rather than replaced by whitespace.

Written by the indexing model from the issue text.