You might want to try a fresh batch of Potassium Oxalate. What ph is your PO? Should be around 5-6. Also you might want to add a little 0.5g Oxalic acid to your fresh Ferric Oxalate.
Also what clearing method are you using? If its stain rather than fog you are seeing you might want trying more aggressive methods of clearing.
If all else fails try a different paper. There are a number of good papers that work well with 50/50 Platinum/Palladium mix.