Liquid dish detergent in the rinse agent dispenser
This may cause a serious subbing problem when it goes to dispense in the final rinse, you could run the machine and see what happens but I think you're gonna have to get the detergent out of there as much as possible.
It's a fair amount of work to remove the dispenser But it is a possibility if you're quite handy.
I've had customers do this, and I take a meat baster and a container of water open the door. Take the cap off the rinse agent dispenser and take a bath towel, lay it all around the dispenser on the inside of the door and just keep flushing water into the dispenser and soak up the soapy water with the bath towel that can be put in the washing machine. You don't wanna flush the soap out just to let it run into the dishwasher either that'll just make a problem really fast.
Hopefully, you'll be able to flush enough of it out that it won't be a problem. You might want to get some simethicone tablets and throw one in with the detergent when you use the dishwasher and if you have a sudsing problem in the last rinse, throw one in the last rinse That will kill the suds very quickly, and it should work its way through, but it will take quite a few cycles in some cases.
Some of my customers simply just paid me to replace the detergent dispenser assembly because they didn't wanna bother with it, but it would probably cost over $200 to have a service call to do this.
John