Applies Value to items in categories NOT selected

I applied a % discount to a single product category. This worked however the plugin assigned a value to the sale price in all other nonselected catagories as 0% discount. This value should be NULL. The way you have made the plugin assigns a value to the “Sale price ($)” value field of items not selected. Causing regular price text strike through and adds a SALE badge to the products NOT in the category selected. I must now go through each product and remove the value from the Sale price ($) field of all non sale items. This is NOT a feature anyone would pay for and causes many hours of work.

Reading through other bugs listed here I see clearly this is a poorly developed plugin as I should not have to deactivate the plugin and manually change prices. Defeats the point.