What could be a reason for cloudy precipitate in PCR reaction with STR Plus chemistry after cycling protocol is completed?

Due to the extreme robustness of the PCR chemistry and the high DNA input volume, elevated local concentrations of certain buffer components might sometimes form precipitates after PCR. These precipitates will not influence the usability of the PCR product. However, we strongly recommend ensuring proper mixing of the PCR reaction after reaction setup and before PCR. Please follow the recommendations given in the handbook. This will reduce local elevated concentrations of buffer components and thus prevent precipitates to form.