SMTL750RM2UC UPS has reversed-polarity outputs?

[JetForMe]

I just received a SMTL750RM2UC UPS, and I'm alarmed to discover that my outlet analyzer thinks the output polarity is reversed. This is the case whether or not it has mains power. I tried to contact support, but they're currently closed.

Now, it's possible my analyzer is just confused, but I suspect it measures this polarity by comparing hot & neutral to ground. Moreover, I'm fairly sure that when mains power is applied, the transfer switch is closed, and the UPS's outputs are connected to the input. The mains supply is correctly wired, suggesting the input cable or the outputs are not.

Update: Upon further investigation, it seems it only encounters this condition when the UPS is first powered on from battery. In this case, ground seems to be at 0 V, while hot & neutral are ±60 V. It's a bit odd, but I think things will be okay. I hope so.