I have tried to recreate your issue and cannot on my version. How are you entering the salt additions for a water profile? Are you making the profile in the water profile tool, saving the salt additions, and then adding that directly? Or, are you adding your base water in the recipe and using the water tab to add the salts by matching your pre-made water profile?
I use the latter method and have no issues. If you made a profile with the salts at the old price and then updated the price later, the program will have saved the original prices as part of the water profile. You can update the water profile or optionally can just click on 'update prices' in the recipe and the program should apply the latest pricing to all the ingredients you have listed.