Maybe don't use dashes/spaces.
When I named my custom song "Chilledwindows" with no spaces, it worked. But when I named the other custom song "Temptation-Before-The-Dawn" (t+pazolite reference) which has dashes (which corespond to spaces ingame) the game either crashes or that weird song glitch happens where the chart just keeps looping every chart beat without the actual song ever playing.