I have been using B&S palladium sol. #3 which is apparently fairy close to a 20% sodium chloropalladite solution for toning. I use 5ml of this solution per 1000ml of toner, plus 5g of citric acid.
My question is: do you use the toner as a one shot? If you are not using as a one shot perhaps the palladium is being used up from the toner and the citric acid is beginning to bleach out the print?
Also, I notice a difference in the colour immediately and only tone for 4-5 minutes for permanence.