I had fluke leads that failed and I blamed everything else not believing that could happen.
I also had "good" leads that had several ohms resistance.
And this not with the CR in particular, just in general. Bad leads can cause a lot of headache, you'd think leads are just wires and can't fail, but with years of use and wear they can internally tear and go from useful to causing more damage than good.
In any case, if you use faulty or not very low impedance leads, the CR benefit of low burden voltage becomes offset more or less severely, even at 1 ohm introduced with bad quality leads that is very significant.
Not saying any of this is what you're experiencing, just what happened to me and some ideas to look into.