That too. Every time I bothered to check, those adjuster nuts were loose. Tighten the way the hell tight again, they'd loosen up right away. I think the poly bushings just didn't deflect enough when one wheel would move up, so it would twist the arms instead, and loosen up those adjuster nuts.
To me it seems to be an issue with thread pitch. IPD used like the most coarse thread pitch they could find, so the slightest amount of nut movement creates a gap. If they were a very fine machine thread it would be a tighter fit less likely to loosen. I have the same problem as you, every other day the IPD junk loosens up. I've tried thread locker with no success. Been thinking about putting a big wave washer between the jam nut and rod but wasn't able to get any 3/4" waves in my area. Thought about hacking off the coarse threads and putting fine threads on, but, probably just gonna get the Yoshifab bars.