Wrong discount calculation between list price and sell price

I have a problem with calculation of discount between list price and sell price. The problem is as follows:

Product: WDTH1034

List price: 150.00€

Sell price: 115.00€

You earn: 13.50€ (it had to be 35.00€)

Total discount: 9% (it had to be 23%)

If you see as the page loads, it shows correct values but when it finnishes loading it change as I discribe.

After searching through out the products I realised that all product that did not have any options, like color or size, the discount was working OK. When I added in those OK products the options then the mistake comes.

Thank you