Okay, so I actually had great results. Not sure this is going to help anyone at all, but I recorded my findings. I had more dialogue and banter within these 2 hours than I have had in 50+ hours of playtime.
Chose group: Iron Bull/Sera/Dorian
Load into Hinterlands
Get on mount, get off mount, rest
Stand outside the camp, not moving
15 seconds - Dorian & Bull Banter
6 minutes - Dorian & Bull Banter
9 minutes - Dorian & Sera Banter
19 minutes - Bull comments on refugees
23 minutes - Bull & Sera Banter
24 minutes - Sera comments on "more hills..."
42 minutes - Dorian & Bull Banter
At 45 minutes I decide to go kill some things, gather, etc (NOT using a mount to get around)
54 minutes - Dorian comments on adventuring
1 hour 2 minutes - Bull & Sera Banter
1 hour 4 minutes - I change my party to Cassandra/Sera/Cole
1 hour 10 minutes - Sera & Cass Banter
1 hour 11 minutes - I go to the Storm Coast and sit outside camp
1 hour 25 minutes - Cass & Cole Banter
1 hour 26 minutes - I leave camp to find some enemies, then went down onto the coastline
1 hour 29 minutes - Cole & Sera banter
1 hour 30 minutes - Got on mount and rode around for a minute
1 hour 45 minutes - Cole comments on "It's quiet"
1 hour 58 minutes - Cass comments on "Ships"
2 hours 1 minute - Run back to camp, no mount
2 hours 4 minutes - Cole & Sera Banter
2 hours 6 minutes - Cass & Cole Banter
So honestly I have no idea what's going on? I'm not too sure what I should test next (I have all day). Any suggestions? I've also noticed I do get music now, and companions are commenting while in fights, whereas they weren't before at all. I was thinking about going to Skyhold and messing around for a bit, then going back to another area like the Fallow Mire to see if the banter still continues.
I will say that the game feels so much more alive with the banter. There was definitely something that was missing before while I was playing, and I think this was definitely it. I hope they can get the bug sorted out though, whatever it is.