Table Filter not working when using measure

Hi everyone,

when I am using the following measure:

LM Change = 
SWITCH(
    TRUE(),
    ISBLANK([LM CY]) && ISBLANK([LM PY]),
    blank(),
    DIVIDE(
        [LM CY],
        [LM PY],
        ""
    )-1
)

I get the following table that outlines last month sales of the current year, it's corresponding sales in the previous year and the percentage change between these two figures per account:

However, when I would like to split each account sales by country by dragging it in the rows-section of the visual,

it says

Can anyone please help me understand and solve this error? 

Thank you in advance!