I have a phone that was using Outlook for Android, it is one of our approved apps. However outlook on the device starting saying it needed to be updated. It would not update, so I uninstalled it from the phone then tried to push it out again. The phone receives a notification to install, but when you select it nothing happens. If I try to install via the Systems Manager app I get the message, "No installation source found for market sources." The device is a Samsung S5 with the latest updates.
There are a few other apps that appear to be giving me the same message when I try to install them.
I have had something similar happen with Samsung phones before. In the case I worked on the phones were only connecting over a cellular data connection, and the default settings on Samsung are to only allow updates over WiFi.
Specifically, we could push apps but they would not update.
So we had the users bring the phones into range of a WiFi network - problem solved.