Unexpected behaviour for Conditional Formatting in a Matrix using ISINSCOPE

Hi, 

Conditional formatting doesn't seem to work for certain levels in a matrix. 

I want to apply conditional formatting in a matrix using a measure.

Using ISINSCOPE the level is determined and which color should be applied.

The DAX statement is as follows:

SWITCH(
     TRUE(),
     ISINSCOPE(fct_mapping[FK Episode]),"RED",        --Layer 2
     ISINSCOPE(fct_mapping[FK Epic]), "GREEN"        --Layer 1
)

For evaluation purposes the measure is used to display as a value as well as the input for the conditional formatting.

In the matrix the expected values are displayed at the correct levels: GREEN of layer 1, RED for layer 2. 

When applying the conditional formatting it seems inititially to work when everything is collapsed.

However when expanding to the next layer the conditional formatting disappears for the first layer and only seems to work for the second layer. 

Any way to keep the conditional formatting active on both layers?