I have a field that is a percent type and I have a smart campaign that either fills or clears fields based on zip code. Anyway, while I can use "NULL" to clear out most of my fields, it will not allow me to use that on a percent field. I cannot type "NULL" into the field, but I can pase it in.
But it gives me the squiggly underline of doom and tells me that "NULL is not a valid number." I am aware of this, but want the field empty and not at zero.
One idea would be to "update" the percent field with a field that is empty. You would accomplish this by using a Change Data Value flow step, reference the percent field, and use the token for the empty field. Maybe a field that you never use but was created by the initial system sync? We don't use the percent fields, or else I would test it myself, but just a thought!