Blackmagic Design MC SDI-HDMI 3G w. PSU

Unfortunately the circuit design with these converters leaves a lot to be desired. While it took firmware updates to even get the LUT loading feature to work as advertised, a even worse problem is that the stability of the 3G Microconverters seems to be very dependent on the power supply used.
Using the USB wall PSU provided by BMD, I can not get any stable signal lock at all. This improves somewhat when powering the converter from another device's USB port but the maximum supported resolution/framerate supported is 1080p30. Higher framerates such as 1080p50 or 1080p60 do not work properly although advertised as supported.
The 3G Microconverters have not had proper QC it seems. The latest firmware update changelog mentions provisioning for "manufactoring improvements" - those are needed, yes...