In the Windows Store edition of MusicBee, under Preferences > Player > Sound Effects, the option to add silence to the end of each track does not seem to work; no silence is added in my case. I tested on three computers with fresh installs of the program. I also tested this option in the portable edition of MusicBee, and the silence was added as expected. Both versions are 3.4.8033. Furthermore, I tested on an old version of the installer edition which also worked as expected.