Access High Sierra partition from El Capitan
I'm still using an early 2011, 15" MacBook Pro. I've installed an SSD, and I made a new partition on it a few years ago. The original part is on El Capitan 10.11.6, and the new one is updated to the newest OS possible for this mac--High Sierra 10.13.6. I'm able to access the El Capitan partition when it's booted up on the High Sierra partition. It just shows up as a connected drive on the desktop. For some reason, when it's booted up on the El Capitan partition, I am not able to access the High Sierra partition. When I open Disk Utility, it shows that there's another partition on the drive called "untitled" (even though it is titled), but it doesn't appear in the drop-down menu. I haven't been able to find a solution online to make it visible. Any help would be appreciated!
MacBook Pro 15″, macOS 10.13