Partially dissolved pods can be the result of adding the pods after clothing, an overfilled washer tub, exceptionally cold water or a wash cycle that was cut short. You can likely remedy the situation by ensuring pods are added to an empty tub, allowing the cycle to run its course and using a warm water temperature when water is uniquely cold during winter months.
If you continue noticing that pods aren’t dissolving completely, consider an alternative like Swash detergent1 that features a precision pour cap for similar dosing convenience without worrying about pod residue.