We investigate the degradation of optical bistability (bistability sticking) in FLC cells with alignment layers of different thicknesses using the static optical hysteresis technique. By storing these cells with and without DC field across the cell and by measuring the subsequent offset of the hysteresis curve we find that all cells exhibit bistability sticking. We find that the degradation of bistability is due not only to ionic effects but could also be due to an additional effect which is independent of the thickness of the alignment layer.