Been looking around to see if others have been experiencing this kind of thing as I seem to come across it practically 50% of the time it seems.
I've ran into some similar issues with the regular 3.5mm jack and headphones before, but it was quite rare over the years, while it's already been fairly noticeable with the lightning headphones and iPhone 7 over a period of just a few weeks.
Unplugging and plugging back in often does the trick, but it doesn't quite seem as quick as it used to be with 3.5mm, where it takes a moment for the headphones to start working once they are plugged back in. A few times I actually needed to unplug and plug back in more than once to get everything working properly, taking even more time, which is that much worse when it's during a phone call.