Creating Conditional color format based on a changing measure

nmyre - First, I would write your measure like this:

Color =
  VAR O = [%Ob]
  VAR TSL = [TSL%]
RETURN
  SWITCH(TRUE(),
    O <= TSL - .05,1,
    O > TSL - .05 && O < TSL +.05,2,
    O <=TSL + .05,3,
    4
  )

Then you would do this:

I attached an example PBIX below sig. Page 8, Table 8.

nmyre - Yes, so in the example I attached, my "Color" measure was called "Measure 5". I set the conditional formatting on "Measure 3", using "Measure 5" as the basis for my rules.

So, in your case, you want to click the down arrow in the Visuals area not on %ObC but on your other measure, %Ob, which you want the color on and choose Conditional Formatting | Background Color. Then choose Rules. Then choose your Color measure and then setup your rules. 

Hope that clears things up.