Not easy to explain and not sure it's VEP related... anyways...:
Vep Pro 6.0.17226 (last version available) used on a MacPro 5,1 12core 3.33GHz, 64G RAM, with ProTools HD 12.5. Mostly use the VEP to load Kontakt instances while recording midi tracks in PT.
Often, but not always, when I record a midi track in PT, notes already programmed on other midi tracks for other patches (IN THE SAME KONTAKT INSTANCE) get stuck, muted, or play indefinitely. Usually I have 4 midi ports enabled on each VEP instance, for each port I have one Kontakt instance with "All" midi channels enabled.
Might be some settings in the VEP or maybe Kontakt/PT related ?
Other settings I have :
Multiprocessing : 12 threads, Audio outputs : 32 per instance, Audio inputs : 2 per instance, Buffers : 2
Thanks !