As the topic says I made party with a friend. After I had gotten to a certien battle level there was a quest that i had to do in a Solo Mission format. After i had finished the quest in question I attempted to rejoin the party as i was it appeared that my friend was no longer in the party

I am unable to click Disband or invite anyone else to the party. as everything is grayed out for me as an option. Me and my friend have tried to log out and see if this resolves the issues, however the problem still happens and i am unable to be in a party at this time.