I just want to repeat that layering samples is working perfectly for me using Groove agent 5 SE.
I’ve just tested it again using two samples from the stock Hip Hop Vault/One Shots folder.
I dragged both samples into the uppermost square on the C1 Instrument Pad and then on the main edit page changed the Mode parameter from Velocity to Layer and then when I hit the C1 Pad both samples play at once!
Is this the way you’re all doing it?
Kind regards
James Colah