Filter less than, more than not appearing

[alex0182828]

This column M for some reason the filter thinks the column is not a number ...

This is how the colum is formatted, there are no values in the column other than numbers
The numbers are generated by a formula.

It so simple but i cant fix this and its driving me up the wall

I want the filter options to appear like this

 

[alex0182828]

If i paste special the column as values doesnt seem to make a difference either
Tried other formatting settings like general & percentage
There are no other filters active on the list
I have added and removed the filter to try and fix it

 

[Scott Huish]

What's the formula?

 

[alex0182828]

=IFERROR(IF(L2="","",I2/L2),"")

 

[RoryA]

That's your problem. "" is text, not a number.

 

[alex0182828]

Aww ok sorry thought "" was blank and would be type agnostic ! Thanks