What PSU are you using? We found that the regulation can make a difference, at least for the LED driving. But the power will actually be derived from the 3v3 on the Waveshare board.
I would suggest to reflow the header pins and try to clean with isopropanol or a contact cleaner. Maybe some flux residues are causing issues. You could also try to carefully reseat the MCU board (making sure to not bend all of the header pins, so lift it up straight).