When running CR mode with my 85xx DC load, changing or toggling different values give unstable readings.

The 85xx series are electronic DC loads, thus the loads are controlled electronically rather than behave like pure passive resistors.  For this reason, there will tend to be some noise and fluctuations introduced when creating and making transitional loading conditions. Additionally, the speed of the processor of these instruments have some limitations, in which case when transitions between load values are too fast, the values will seem as if they are jumping or become unstable.  The unstability specifically applies to CR mode because the load will Calculate the resistive value based on measured current and voltage at any given time, which takes additional time.  When transition is too fast, the load becomes unstable as it does not have enough time to complete the calculations.