Do you have a high drain loop? Was the knockout plug on the disposal fully removed where you attach the drain? Are you running the hot water at the sink to prime the line prior to starting the DW? Is 2 brands of DW detergent all that you have tried? Have you tried a powder with enzymes? Kirkland from Cosco gets top marks with hard water.

It sounds like you should try dialing back the amount of rinse aid dispensed. The owner's manual tells you how to do that.

Thank you both for the advice. I actually read about it today that excess rinse aid can cause slimy dishes. I tried dialing down the setting to the lowest for tonight’s load and will report back tomorrow if it helps. I’m also looking into the powder detergent.

my guess is that it is insuficient rinsing of the detergent off the plates - you would be feeling detergent residue. Check the drain connection and the air gap to make sure that they drain water is actually exiting the DW. The air gap may be causing the water to slow down, not get to the other side of the high loop and then slide back into the DW laden with detergent