When doing a reservation, the system will use banked points first if, and only if, the member has actually banked them before doing the reservation. What you are seeing indicates that the member likely did the following: (a) made a reservation for the 2017 use year that used up both 2017 points and borrowed 165 points from the Aug 2018 use year; (b) circumstances changed and the reservation was modified, possibly by switching resorts at 7 months out, which left 39 2017 points left over which were then banked into the 2018 use year. That scenario would explain why there are 165 points already gone from the 2018 use year even though there is likely no reservation existing in that use year --it is right now early Aug 2018, the beginning of that use year and the owner should not have an existing reservation in place to be taken in the future if trying to sell the points. It also explains why the 2017 points were banked because those 165 points borrowed from 2018 could not be sent back to the 2018 use year and thus when the 2017 reservation was modified, those borrowed points got used first before the current 2017 use year points (which the system would also do). That scenario also explains why the member has not attempted to reallocate the banked points to a reservation in the 2018 use year using 2018 points
That is the likely scenario. Another less likely one is that the member could have sold and transferred the 165 points from 2018 to someone else.