Got it working with your settings, but only using the manual feature code ## EXT # It will not work with the transfer button on the phone.
I am testing this with a Distro version (FreePBX version 13) and all current module updates. It was only after reading your message that I tried ## option instead of the transfer button on the phone (silly me).
I will also follow up with my Grandstream support case to inform them of the findings, so they can correct this in future firmware.
Thanks for everyone’s help.