Iv also had this bug happen to me but i couldnt go back so iv started a new game but i had so much unlocked I dont know what happened but next thing i knew Ryen was the only party member some of the others were in the castel but wouldnt be alowed to rejoin me. Not sure but the last two things i did befor i noticed that was i got annoyed with the Begus Officer only haveing the option of leaving him alone and provoke him so i finaly proved him and beat him then i visted a fort and either talking to the nightwatch guard who has his tent set up on the wall or the storehose in the same location being locked triggered it