When you added the 2 new cams did you enter the IP, user/pass into BI and hit "Find/Inspect" ?
Foscam has monkeyed with ports over the last couple of years and/or firmware revisions from what I've heard.
The HTTP port in earlier versions is 88, not the standard 80.
I'd check to see which is appropriate for your new R2's by putting its IP into a browser and hit <enter>.
If the cam's webGUI does not open, try the IP again but this time add :88 at the end of the IP and hit <enter>.
Come back if no joy and we'll talk about scanning camera ports.