special I did some device-tree archaeology on the Linux 3.14.y sources (used in LE 9.x images) and HardKernel 3.16.y sources.
LE sources only describe the basic "highspeed" card mode and max-speed as 100MHz. HK sources support highspeed and UHS 50/104 card modes, but a lower max-speed of 85MHz. The upstream kernel describes highspeed and UHS 12/25/50 (and DDR50 for some reason) but not UHS104, with max-speed set to 100MHz.
The current image here: https://chewitt.libreelec.tv/testing/LibreE…droid-c2.img.gz aligns the upstream kernel controller capabilities and speeds with the HK vendor kernel (remove UHS12/25 and DDR50, add SDR104, reduce the max-speed to 85MHz). Please write to a card (the problem card) and see if that makes any difference?