The following may be the reasons why they don’t dissolve properly:
You did not place your laundry detergent pods at the bottom or back of the washer before you add your clothes.
The water is too cold. Dilute the pods in hot water first before you pour them into the drum during winter.
You overfilled your tub with garments. Only fill ⅔ of the drum with loose clothing.
Don’t use too many pods than necessary.