I can't explain it.
For some people the device works without problems, for others it doesn't.
What could be the reason for this? Has the design of some devices been changed, different chips used or something similar?
Agreed. I've posted here before, and wonder a lot about why it be so very different from user to user?
(For instance what is the point of having a high setting when it only works on, let' say... 1-5% of all devices? What is the reason for it NOT working on high for the rest of us?)
because the design depends a quality usb-c cables with a proper chip inside them.
Also constant 24/7/365 power draw keeps a lot of heat on the chip in the unit and the usb-c cable's chip.
This gear will not last at high without an effort to cool the 2 chips.
Stupid design flaw.
best way to understand this is to put an infra-red temp and check the heat where the 2 chips meet.
shame as I do like it. I suspect this will break on me this winter as I have run them near an ac/heat vent once the heat comes up in the winter I think these will break.