Have had this issue since the beginning with Synchron Strings in Pro Tools:
Instantiate an instance, record a performance, and everything plays normally.
Then after about 20 minutes, Synchron Strings will play only the first second of the line you reoorded, and then it goes silent. It sounds like some controller is pulling the volume all the way down quickly. But that's not what's causing the problem.
I've dealt with this for the last year by rendering the MIDI to audio. I think this mainly happens with the legato presets but I'm not sure.
Any idea what's causing this?