Change a reservation function doesn't seem to properly apply weekly or monthly rates

[Matthew20]

Hi Follow hosts,

After I accepted a 4-guest stay reservation request for 7 nights with a 10% weekly rate disount, my guest wanted to modify her stay down to 3 guests.  When I changed her reservation to 3 in the "Change/Cancel" screen, I would have expect the new charge to apply the same weekly pricing discount in the calculation, so the reduction should have been = $157.50 ($25/person * 7 nights * .9).  However, the rate was reduced by $175 ($25/person * 7 nights) omitting the discounted rate.  Is this a known bug or am I missing something?

Thanks,

Matthew