Thank you for reporting it! I just tested it, and you're right! It's a weird behavior. I couldn't manage to make it work properly yet, but I've made a workaround that prevents the BGS from being played if the volume is set to 0%, otherwise, it plays at 100%, but I guess it does the trick for those who want to play with BGS disabled. It will be implemented in my upcoming update, and I'll try to make it work properly. Meanwhile, you can just apply the patch yourself. Just extract this file at the root folder of the game and replace the file rpg_objects.js when you're prompted.
Thanks again! Feel free to directly report any other issue that you find! (instead of saying "looking at you escape from misantria" in a thread that I rarely check

)
JK, seriously, thanks!