Hi I am tech Michael, there are a few reasons this can happen.
Once you check all that, I will help you determine which part(if any) is needed and I will help you replace it;-)
Check the water temperature. Should be 125 to 140 F. (this is important.. check your hot water heater to make sure that it is turned up well enough to give out hot water)
Check pump re-circulation., Listen, see if it sounds like it is spraying the water around with enough pressure.
Check water level when the fill cycle has completed. Should be just under the heating element. If not, possibly need to replace the water inlet valve.
Check the spray arm and pump cover for splits or leaks.
Check to make sure dishwasher is draining after each cycle. There should only be a little water in the bottom of the tub.
Make sure the dishes are loaded properly, or dishwasher is not overloaded.
Possibly try a different detergent. Some liquid-gels will bubble and a pump cannot pump bubbles
In any case, I will stick with you until this is complete.
Please rate my service kindly.
Also it is the only way I am credited for my time and expertise with you.
Once you rate, I will be notified and will add your question to my priority list so you can reach me anytime until this problem is solved.
Then you can reach me by simply replying to this message anytime.
Thank you and have a great day!