The parameter value in workbench likely not recognize the change to driving dimensions made by script:
dims_NS = Window.Groups.GetValue(Window.ActiveWindow) # gets list of named selections and driving dimensions in Groups tab, not published scripts or script parameters
dims_NS[0].TryGetDimensionValue() # 1st dimension, 3-tuple type. value is index 1, type is index 2 (Angular, Arc, Area, Diametric, Linear, Mass, Volume
dims_NS[0].SetDimensionValue(value)