Try walking up to where the NPC is meant to be, - press "alt+O" (for options).- click "Alternate Models" (left hand row).- check or uncheck any random race/gender. (this forces a model reset)While I have not had the Y-axis render issue myself, this is what I have told people having problems to do if the bug occurs. In most cases, this has (temporarily) resolved the issue. Doesnt prevent the bug from happening to begin with, but saves doing the full relog.