I have installed 4 price sliders from 3rd party extensions and in each one I am facing the same issue. The slider is not functioning the way I would like it.
For example, we have products from $99 - $200.
But on some of the products, the custom option is set for drop-down with different sizes of the product with a higher price for the larger product.
Product ABC is $99 but you can select the larger product from the drop-down menu for +$50 more.
The price sliders are displaying and filtering the products with the additional prices in the custom option.
The slider will display the range of $99-$200 but when you filter the slider to $120-$200 it will still display product ABC, even though product ABC is $99.