In my experience some patches don't sound because the part parameter ARP is On. Switching it Off was a solution.

__ if the ARP PLAY ONLY parameter is set to On, and you turn the Arp Off or don’t assign/import the Arp as originally set, the instrument does not sound from you touching the keys (it is set to only respond to data coming from and Arpeggiator). Some third party Libraries suffer from this malady.