2 answers:
1: you must upgrade the firmware on your 5D and or P30 - old firmware doesn't recognise the new ultra- large cards. its not hard to do and pretty straightforward. do it on the 5D first (use a different CF card) and follow the instructions Canon give. Then try to re-format the 32Gb, and see what happens. Formatting in a canon and then a DB should make no difference, you have done nothing wrong.
2: if 1 doesn't work, and the 5D still shows 8Gb only, then you have a faulty or counterfeit card. This is not as unusual as it sounds. if it was a really cheap card that seems too good a deal to be true - it probably was. Move fast on this, you have 30days with PayPal only to get your money back. There'sa lot of bad cards out there with false capacitiies, and even if they are the size they say, they write at the speed of a snail, and are near unusable. avoid. best to get known brand cards from a proper US supplier. I speak from experience!