Tax class reverts to Basic in product

Hi everyone,

This is my problem.

I have setup taxes, I selected Prices Including Tax, then I set up the tax classes. I used one rate for “Standard Rates” (Vat 24%), one for “Reduced” (Vat 13%), and one for “SuperReduced” (Vat 6%).

Now, when I edit a specific product, if I want it to have a 13% VAT, instead of the standard 24%, I should change the tax class in the product from “Standard” to “Reduced”, right?

Well, every time I do this, after I save changes, the tax class in the product reverts to “Standard”!!
I even tried to delete the rate in “Standard” to leave it empty, and made another class named “Regular” in which I created one rate for Vat 24%.

I tried again and the product still keeps the “Standard” tax class…

I am confused. I don’t think I am doing something wrong here, but I don’t see anyone else having this problem!

Any help will be appreciated.