Please change Potassium Sorbate with Sodium Benzoate to see if your precipitate is Potassium sorbate . You are using 0.05% of Potassium Sorbate which is too high unless you are providing the diluted drink, with all its preserving action as well,
hence my question. If not, you are over preserving. Your country food law will also have limits in beverages and you can gauge if you are on upper limit.
High dosages of preservative leads to a burning sensation in throat when drinking.
Please use a total preservative amount of 0.02% in a small trial. If using Sodium Benzoate solves your problem of precipitate, you know it was not necessary Potassium Sorbate, but the high amount you were using.
You can also, try 0.01% Sodium Benzoate and 0.01% Potassium Sorbate together if Precipitate has disappeared. Other ingredients that Precipitate are sugar haze or fines, cloudifiers, Hydrocolloids that are not very cold water soluble etc. Put sodium Benzoate as second ingredient before Citric acid.