CAPE-OPEN

hi. I decreased the number of stages and monitored the reflux ratio, to note the crazy jump in reflux ratio to determine the minimum number of stages using the rigorous approach. to my surprise there was a jump to a high value on stage 16 (see attachment), and then a drastic fall on stage 15. my question is shouldn't reflux ratio increase indefinitely as we decrease the number of stages till the column does not converge due to stages being specified being less than the minimum. thanks