Percent of Total Rank

[KeatonO]

I have been stuck on this for over a week now and am going a little crazy! I truly appreciate all the help that can be given. 

End Goal - Use conditional formatting to highlight the bottom 25% of the selected Revenue Rank. 

Current Workaround Goal - Divide an agent's Revenue Rank by the Max Revenue rank Selected. (I can then use that percent to identify the bottom 25%. 

Ranx formula

I have tried getting MAX([Revenue Rank]) to say [Revenue Rank]/Max([Revenue Rank] but that doesn't work because Revenue rank is a measure and MAX only works on columns. I need to find this bottom 25% on only the selected data which filters to only one department/role. 

I have tried getting the max number with count rows.

but it references the count of the invoiced sales data 298 instead of this department/role which currently has 41.

I have also tried creating a table and splitting it by quartile. 

But it's not quite right, it's close but will only work with the full invoiced table and not with the filter to look at just outbound supplies. With the filter it looks like this.

Even without the filter it's not quite right. 

I have looked into top N and couldn't quite get it right either. 

Please help. I think I am overcomplicating this but cannot for the life of me figure out how to highlight the bottom 25% of the Rank.