We have been upgrading our MXs to the 16.x release train to take advantage of the newer classification achieved using NBAR, however in our experience it seems worse as now ~90% of our traffic is classed as unknown. At least before it would come up as Non-web TCP - [remote hostname] and be divided by the remote hostnames:
Here we can see two internal clients talking to one external host, however now, as seem below, this traffic and a load more is all lumped together...
Here we can see that almost all traffic is now unknown, you can see when we upgraded...
If my answer solves your problem please click Accept as Solution so others can benefit from it.