There is not confirmed hardware problems related with the PoE-Out on these devices. PoE out status is dependent on multiple factors, for example, the voltage drop on the wires which powers your PowerBox, and the voltage drop in the wires that goes to the powered devices, both will cause current flow to increase. If the total or port current limit is reached, the PoE will be turned off.
At first, I would suggest you to update your RouterOS to the latest RC version, where PoE logs are added, you will see the reason why the PoE is disabled.
In case if you are powering multiple devices, change the problematic port priority to highest:
https://wiki.mikrotik.com/wiki/Manual:P ... p_priority
If the problem remains, plug problematic device to some other port
If the behavior is the same, generate a supout file, and send to
support@mikrotik.com, with a description of your setup.
https://wiki.mikrotik.com/wiki/Manual:S ... utput_File