We're about to upgrade from 2.14.2 to 2.16 and I ran through the process in a test environment. When I logged back in after the upgrade, I could not see my volumes and nothing else along the blue menu bar (Directory, Infrastructure, etc.) was showing any information. I had seen posts in this forum about database fields/values that caused some other "missing volumes" issues but found that my problem was browser based. I ended up clearing the cache in my browser (Firefox ESR 60.6.1), logged back in to AppVol, and everything showed up correctly.
Wanted to put this up here in case anyone else ran into the same issue- You may not need to start poking around your database!