Slicer issue with blank values and zeros

This is not only a slicer issue but also dax functions of IF and SWITCH

Example measure=

var _test=[a measure] \\ format as decimal

return

switch(true()

 ,_test>10,"A"

 ,_test>=0,"B"

)

In this situation whether [a measure] is 0 or blank Example measure returns B

But if i rewrite it like this;

Example measure=

var _test=[a measure] \\format as decimal

return

switch(true()

 ,_test=blank(),"blank"

 ,_test>10,"A"

 ,_test>=0,"B"

)

then this returns "blank"

this is not reasonable