Ugh, yes. This keeps happening all the time, to almost everyone! Sometimes, the game took both party slots whenever we tried to return. Most of the times, these parties have already glitched, the 400 error! The team should work out on this soon, or maybe remove the glitched party from list, so we won't accidentally join in and waste party slot(s). I always love returning to parties but somehow this glitch makes it impossible for me to do so. Not only we missed on the party rewards, but those party slots...those precious party slots...we only have two for every reset...maybe we need an increase? But still that won't solve the issue. Please fix it ☹️