Sorry for seeing this late. 360 photos need to be added into your pictures/360 photos folder. The latest update adds a button that lets you open that folder in explorer. Anything that gets added will show up in the photos tab.
The release was pushed back by a couple days so that I can provide Oculus Home keys with every purchase on Steam; this will allow you to have access to the app from Oculus Store and launch it from there.
The old MSI installer caused this mess. I moved away from it but uninstalling the old one will be a pain. You can just wait for the release on Steam in less than 2 weeks and that will solve your problems :-)