Directed call pickup from ring group not working

Using Asterisk 11.10.2, FreePBX 11, and Polycom endpoints with UC software 4.0.6. Using proper SIP call pickups, not a feature code.

This works fine with calls going directly to an extension, but calls coming into the same extension via a ring group cannot be picked up by the remote endpoint. I see this in the logs:

NOTICE[1883][C-000147f5]: app_directed_pickup.c:302 pickup_exec: No target channel found for [email protected]

Does anyone have a similar configuration working? I believe it was working on an older system (Asterisk 1.8.7, FreePBX 2.9, Polycom UC 3.3.1) without issues.