Conditional Formatting Blank Result Bug

I have a measure which displays "-" if blank, the conditional formatting which turns the font red is being applied when this result is returned even though the two rules applied are

1) red if less than 0

2) black if blank

I'm unsure as to why this would be happening, Power BI considers this a blank or the result wouldn't be - but it's conditionally formatting the text as a negative number at the same time?