Roberts exited four pitches into his rehab appearance Sunday with Triple-A Iowa after suffering an apparent aggravation of his right shoulder injury, Alex Cohen of Marquee Sports Network reports.
Roberts retired one batter before calling for the training staff and exiting the rehab appearance, which was his first since landing on the 10-day injured list May 1 before he was later moved to the 60-day IL. The Cubs should provide further word on the extent of Roberts' setback in the days to come, but he no longer looks on track to be activated when first eligible in the final week of June.