Curiosity question: Does the UPS being used have sine wave output?
SMT1500RM2U and SURTA1500RMXL2U do.
With the management card installed the setup can be tweaked.
Under Configuration --> Power Settings one can set the voltage thresholds and sensitivity. I suspect that the PSUs in the JBOD are just a tad bit too sensitive to incoming power fluctuations. The UPS settings should be able to be fine tuned to your given environment. Ours is terrible. We have lots of power fluctuations and usually two or three power outages due to someone putting a shovel through a line somewhere.