Formula working when Drilling in matrix table

Struggling to work out the formula to be able to drill up and down a matrix table but keeping the formula working for each row

the below matrix table has a set of formulas running. this will work for each month as it stands below
but if i wish to group by the quarter or further up by just the team total, the formula provides incorrect values. i know my formulas would be wrong and its not filtering the right parts. any help would be great

my formulas as below

Density = DIVIDE('Created Bugs','Days)

the below is to determine the target for the July to August period but then define this as the target for all periods going forward
Target =

CALCULATE (

'Density',

DATESBETWEEN('Date'[Date],DATE(2021,07,01),DATE(2021,09,30)

)

 

This is where i think i am having trouble with, this formula is just the standard calculation. ive tried with FILTER, ALL, ALLEXCEPT and i know i am doing something wrong but cannot determine what. in the above screenshot it is working fine when it is calculating at the month level
but with the below screenshot when i start to condense or drill up, the formula fails

Density % difference =

DIVIDE( [Target] - [Density], [Density])