I use a custom theme in my Magento store but in version 2.2.9 the special price is not being considered in the final price of the product. In version 2.2.2 everything worked normally.
This happens on the product page and even in the cart.
If it were a code problem all products would be displaying the wrong price, but some products display the special price and some not. All the products I mention are with special price set.
Following are images to exemplify:
I'm Just using:
$this->getProduct()->getFinalPrice() to get final price (so if has special price have to display special price as final price)
But when i debug the object $this->getProduct()->getFinalPrice() for the first image returns 99, but for the second image returns 239 but the correct is 149 because special price is set with 149.