Using FMPA 17.0.2.205 on Windows 10.

I have a number field in a record that is empty (no value entered):

Isempty(Field) correctly returns 1 (True)

Field = 0 incorrectly returns 1 (True)

Field = 1 correctly returns 0 (False)

Obviously the second result is wrong since an empty field is clearly not = 0.

Is this a new bug?

No, it is the correct result, because you are comparing a Number field to a numerical constant. Therefore, the comparison will be done numerically, and the empty field will be forced to a numerical value of 0.

You will get a different result if you do the same thing with a Text field.