My SD Card Reader has never worked in Ubuntu on this Dell XPS machine since I got it over a year ago. I never fixed it because I hardly ever use it but I did have a need to use it today so I Googled my issue and found a very simple fix. I just had to add “pciehp.pciehp_force=1” to the end of the GRUB_CMDLINE_LINUX_DEFAULT= line in the file /etc/default/grub. Then I ran sudo update-grub and rebooted and it works every time now.