WS-12-250-AC - Sporadic unresponsiveness/power issue?

[brian.onsite]

Unit periodically goes unresponsive. When physically inspected, the power light of the unit and the right LEDs of all POE ports are flashing in unison.

In these situations, unit cannot be reached at all remotely, and even a single power-cycle does not resuscitate the unit. Only hard power down and removal of all load allows for a proper cold boot.

Voltage usage while able to be monitored is between 22 and 44 watts, nowhere near the max of 250.

POE ports are as follows:
1
2 24V
3
4
5 24V
6 24V
7 24V
8 24V
9
10
12
13
14

As you can see, nowhere near full load for a 12-port switch.

Problem has been experienced on v1.4.2, v1.4.3rc7, and v1.4.4, and after the incident recurred tonight we upgraded to 1.4.5rc2. The units on the POE ports are known good Ubiquiti M2 and M5 units (three RM3s, one BTM3, and one PowerBridge M5 to serve as a backhaul for the tower). These units have shown no trouble hooked up to an unmanaged (dumb) switch and individual POEs.

Is this just a bad unit for RMA, or is there something we're missing here? Similar forum posts with these indicator lights have involved unusual setups such as hooking a switch to an alternator for configuration, but this has at least previously been a stable location for us, with proper grounding and a UPS to prevent power fluctuations at the site being an issue. We have deployed nigh-identical physical configurations at other locations for WS-8-250-AC switches we have in use, and this is a higher-end switch that we certainly wouldn't expect to have more problems with such an environment.