AC300 ignores SOC low setting (but not SOC high)

I have an AC300 hooked to one B300. When I set the SOC Battery High and Low settings, the high is honored, but the low one is always ignored, and the battery runs down to 0% and shuts off. Anyone else seeing this?

I have the AC300 set to Customized UPS, Time Control Disabled, Grid Charge Enabled, Battery SOC High at 85%. I’ve tried setting SOC Low to 5%, 15%, 20%, 30%, 50% and more and they all get ignored.