Currently audio player is packed without Network and udisk access. Network access is required to be able to play internet radio. Also, Elisa tries to access org.freedesktop.UDisks2 on System bus . I don' t know why, to be able to enumerate plugged in drives? Allowing it removes error so.
Looks like you also filed this at https://github.com/flathub/org.kde.elisa/issues/87. No need to do so here as well, as the changed need to be made over there.