It looks like there is a deeper problem with BLANK() not working with the != operator. I made a blank column that only had one row with a value called Column1 and then another column using the function Column1 != BLANK(). It returns 1 for all rows, even though there is nothing in all rows except 1.
Doing Column1 = BLANK() returns the correct result (all rows 1 except for the single row with a value in it).
The best solution I found is to use the NOT operator. Doing NOT(Column1 = BLANK()) returns the expected result – all 0s except for the row that has an entry.