"Open Enclosing Folder" keyboard shortcut (Cmd-Up) Disabled in certain folders.

I use the command-up / command-down arrows constantly in Finder to navigate between folders. I recently encountered a situation where I could not navigate "up" to the enclosing folder using the shortcut (or the corresponding command on the Go menu). After unsuccessfully searching for a solution on this forum, I discovered a fix and wanted to post it here for others:

In my case the affected folders were on Dropbox, but I think this might apply to any cloud storage service like iCloud or Google Drive. I could navigate into the folder using Cmd-Down from the enclosing folder, but then could not return using Cmd-Up. I turns out that there were some incorrect file permissions that prevented me from navigating back to the enclosing folder.

I simply navigated to the top of the folder hierarchy in Dropbox containing this subfolder, and using Get Info I accessed the Sharing and Permissions pane "Apply to enclosed items..." command to repair the file permissions on the affected items. You'll need to click the lock icon and enter your password (or Touch ID) to change permissions.

That's it, hope this is helpful to someone else!