I implemented Facebook SDK in my Android app for event logging. Events that are sent while the app user is authenticated (i.e. logged in to Facebook) show up in events manager. However, events sent in a state where the app user is logged out of Facebook don't appear in Events Manager. I verified using FacebookSdk.setIsDebugEnabled(true); that they are sent successfully, though. So I wondered whether this behavior is intentional or whether it is a bug?
(facebook support hasn't been helpful so far)
I found out that this behavior is intended (but undocumented...). It is normal that Facebook Events Manager doesn't show all events that are sent by Facebook SDK. If you want to debug your code, go to Facebook's App ads helper and launch your app using a deep link. This guarantees that events will show up (at least in my testing).