Currency Conversion with Custom Fields is wrong

[Basementality]

I have just installed and set up the 1.3.7 over at http://www.basementality.net/shop
while using an almost identical setuo with Prestashop 1.1 at http://www.basementality.se/shop

Problem starts when entering custom quantity blocks for products:

- Custom attributes are set to let buyers select 50, 100, 150 etc items at once.
- Each attribute except the lowest default value are set to increase the price by an amount in default currency.
- This works for the default currency

When changing to the secondary currencies the items on the category front page have the correct conversion numbers
- Once you go to the product page the default value is reset to some number much lower than the original
- the attributes are added on correctly but the default price is all wrong so that the totals are messed up as well
- Since the default attribute is not changing the base price It seems that something goes wrong once this value is selected in the table and some miscalculations seem to be performed

Note: Exactly the same setup in 1.1 Works just fine!
This means that the conversion rates are set and work just fine until the product page hits

Any clues why this happens??

Thanks in advance / Happy Prestashop user