Last month, Nguyen had told ESPNFC that he wanted to move on from the Revs after spending six seasons in Foxborough, believing the club owed him the opportunity for a new challenge after an extended run of service.
But before camp began, New England coach Brad Friedel insisted the creative midfielder would not be traded and was in the first-year boss's plans.
That difference of opinion led to Nguyen's staying away from the early stages of preseason camp.
Now he appears to have returned. But there's still a chance Nguyen could be dealt within the league before the MLS primary transfer window ends, or later this summer when the secondary window opens up.