Hey norman74 Okay... I fixed the 'progress bar not loading' problem...
The problem now, after testing the app, with two Android phones (to see if the real-time is working correctly), is that once I write data into the textbox and press the save button, the data's still (like before) not being sent in "real-time" to my other Android phone.
What else could I be missing? What's creating this connecting problem?
Do I need to use the FirebaseAPIV3 "Initialize" function, on start of layout? As well as, the Firebase plugin's "Go Online" function?