Excel 2019 conditional format (numberformat) doesn't seem to work!

I've a simple spreadsheet with a column of 3 numbers:

-15.3, 9.67, and 22.14.

I've created two rules (with color) with number formats with 0 and 2 digits. When the named cell TT_R is 0, I want whole numbers. When the cell is non-zero, I want 2 digits.

However (as shown above) the first rule (TT_0=0) never seems to fire!

Why and any ideas?