Google Hangouts: Conflicting online status information Another "I don't quite understand what is going on in Google Hangouts" type of question....

So - when I view Hangouts via my Android app (running under KitKat), my girlfriend's status is ALWAYS shown as online (green speech bubble next to her picture), even when she is not online.

Conversely, if at the same time I log into my GMail account, her status is  shown as NOT online (no green line under her name). How can she be both online and offline!!?

What the hell is going on here?! Has anyone else had this issue?
Once you sign-in to the Google Hangouts app in an Android device, you will always appear online until you sign-out of the app.  Shutting down the phone, or even uninstalling the app won't do it.  I'm not sure why she appears offline in Gmail.