Since upgrading to Ubuntu 18.10, I cannot access one of my partitions (see image). Gparted shows me that it is still there but I cannot see it in nautilus. Any idea how I can access the files on this partition?
Gpartd seems to be saying /dev/sda8 is mounted on /home. If you open nautilus, and it does not open in /home, try scrolling to the bottom of the left panel and selecting "+Other Locations". Then click Computer, which should show you a list your disk root. One of the directories shown should be Home. That's the one you're looking for. Assuming that you are logged in as a user, you should see your user name in there. That's your home directory.
Nautilus tries to protect you from the fact that your home directory is not the mount point. On my system, it shows a little house to the left of "Home" with a capital H at the top of the panel when I access my home directory. When I access the mount point, it shows "home" all lower case.