Use faux TSP to clean them. I use about one tablespoon to 10 coffee cups of water. 2 minutes agitated in warm but not hot water. Then dump, and rinse well.
I use a dollar store salad spinner for this, as well as for the mineral oil-water bath method to prevent dryness after cleaning. The basket comes in handy. I use very little mineral oil, but still like to hand wipe each chip with a microfiber rag after they’ve sat a while. (Best done while watching football, the WSOP, whatever.)
I have an ultrasonic but have yet to encounter any chips dirty enough that the above method did not suffice. Occasionally I’ll find 1-2 chips that need some TLC with a toothbrush/toothpicks, but that’s it.
There are endless posts about this stuff in other threads. Search “faux TSP.”
I can’t imagine why RHCs would have become hard to shuffle after basic cleaning unless you used some detergent which somehow didn’t get fully rinsed and is clinging to the chips.