Alright since Nexon doesn't like fixing stuff that doesn't directly kill off their income, we'll be living with the party glitch for a while. That means every now and then you'll be stuck in a non existent party. When that happens, you usually log off to remove it. However if you're doing a partner quest or something else that doesn't require relog (or doing skill training and relogging after every SM is annoying), you may wanna try:
1) Get a friend/alt to make a temporary party on the party board on the same channel
2) Hit "P" for the party menu
3) Hit the "Party Board" button
4) Join the party made in step 1, and exit
5) Glitch is removed and you may now make new parties/join SMs
