For me it seems like banter and music work as intended for me, IF I'm just idling around.
I'm no coder or anything, but it really feels to me like a priority issue. As in, the party member to party member banter seems to be lower priority than environment comment and quest comments. I say that because, when I'm walking around doing stuff, exploring/closing rifts/setting up camps, I would get very little member-to-member banter, but I would get one-liner comments like, "Ouch." "That's rather grisly." "This desert is so big." etc., as I pick up quest items and whatnot.
I do consistently get music as I'm exploring. Consistently getting "combat banter" as well, such as when combat ends, party members will say taunts like, "One down!" During combat, I'd hear things like "Kill the warrior!" "Solas needs help!" I also noticed is that things like "We should set up camp here" takes the place of intra-party banter. Because sometimes I walk up to a camp site I haven't claimed yet, and nobody in my party says "This looks like a good place to camp." Then about half the time, right after I claim the camp, I'd get a banter right away. If someone said, "This looks like a good place to camp," I would claim it and then no banter.
Anyway, it was still bugging me because while it's nice that I get the combat/exploration/questing comments, very rarely do I get party members talking amongst themselves. Which is why I think even more that it's an issue with priorities.
So I had some work to get done over the weekend and I thought that was a good opportunity to do some idle-in-a-camp testing.
Loaded up an Autosave 67 hours into current playthrough, in the Path of Flames camp in the Exalted Plains. Turned around and walked to the World Transition point instead of bringing up World Map from the Menu. Party is Vivienne, Sera, and Blackwall.
Quick Traveled to Hinterlands, Redcliffe camp (the camp, not the town). No mount/dismount. No resting. I just accepted the Requisition and idled in the camp from 1:22 p.m. to 4:58 p.m., and I think the pattern I got is what's intended.
The background music triggered like clockwork, every 2-3 minutes I would get a clip of music for about 7 - 20 seconds that has a natural-sounding fade-out.
In the 3.5 hours of idling, I got 22 banters, counting one-liner comments on environment. I got a healthy variety of A with B, B with C, A with C.
First one at 4 minutes
Then 9 minutes
43 minutes
46 minutes
56 minutes
57 minutes (yes this one was back-to-back pretty much)
69 minutes
73 minutes
76 minutes
86 minutes
93 minutes
103 minutes (Sera one-liner comment on environment)
113 minutes (Blackwall one-liner comment on environment)
128 minutes
131 minutes [Followed by the longest silence yet, but music still triggering every 2-3 minutes]
169 minutes
171 minutes
175 minutes (Sera one-liner)
186 minutes
195 minutes
210 minutes,
and finally one at 215 minutes.
I noticed that the one-liner comments seem to take a "slot" of a member-to-member banter. One more reason that makes me think it's a priorities issue.