Ring Groups and Transferring A Call

I currently have a Ring Group setup for when callers press 0 in my main IVR. This Ring Group is setup with a ring strategy of ringall and rings 4 extensions. When a user answers a call from that ring group and they need to transfer the call to another internal extension, the call does transfer. However, if the recipient is unavailable, the call does not go to voicemail and the caller is then disconnected. This only happens when a call is routed through a Ring Group. If a call goes to the initial extension directly (not through a ring group), the user can transfer the call with a successful completion to voicemail if necessary.

Any ideas or suggestions would be appreciated.