They are not stranded however they will keep longer: NASA talks about astronauts | Illawarra Mercury

The take a look at flight was anticipated to final every week or so, sufficient time for Wilmore and Williams to take a look at the capsule whereas it was docked on the station. However issues with the capsule’s propulsion system, used to maneuver the spacecraft, prompted NASA and Boeing to delay the return journey house a number of instances whereas they analyzed the issue.