"Debt ceiling talks break up with negotiators unsure when they’ll next meet"

What do they mean they don't know when they'll next meet? The stock market fworldwide for starters will be taking a big dive next week if this isn't figured out.
A US default could happen as soon as June 1st and so what else do they have to do but meet and figure this out. What else do they think is on their plate but this?