I know i'm a little late, but i feel this should be addressed more fully. For anyone that might see this, the "notes hanging" thing with CineSamples's libraries (and some other ones too) where the notes end but keep playing even when the song is paused, is very likely a bug with the legato engine. This bug happens more proeminently with CineSamples CineBrass, but i've seen people complaining about this happening with CineStrings, CineWinds and even other libraries like Cinematic Studio Brass. I myself have encountered this bug a few times.
My guess as why this bug happens more with CS is because the engine that CS uses for legato is always calculating when you play a long note. Why? You see, you may have noticed that CS libraries don't have Sustained only patches, only Legato patches that can be turned on or off for Sustain, so every time you play a long note it will calculate for Legato by default. Some times, depeding on the notes you put down, the engine can go nuts and frick something up while calculating, and thats when the bug appears. There isn't exactly a "fix" for this bug but you can prevent it from being an annoyance by doing as follows:
As the bug is almost certainly a problem with the Legato engine, then just turning it off completely should solve the problem. If you want to use Legato however, then you can do differently: You can identify the notes which are hanging, and using your favorite automation method, turn off Legato while these notes play, and then turn it on again. This is what i do when i encounter this bug and it never failed me. This bug tend to appear during chords, so it's a good thumb rule to turn Legato off during chords that are not connected (connected i say cuz the poly legato thing). Speaking of it, i am not sure if the poly legato feature is somehow responsible for the bug happening with chords but you can experiment with it if you want. Maybe turning only the poly off solves the problem?
I hope this helps you somehow, cheers.