It did end up being a channel issue. The AP-105 mesh portal was using channels 36 - 48 and the AP-275 was using 153 - 165. I disabled channels 36 - 48 on the Regulatory Domain used by the Mesh APs and the AP-275 Mesh Point was then able to mesh with the AP-105 Mesh Portal.
I also disabled scanning on the ARM profile used by the AP Group that formed the Mesh. Not sure if that had anything to do with it, but Aruba TAC recommended it.
The Mesh now uses 802.11a for the Mesh backhaul and 802.11g for Wireless clients. Seems to be working fine. The distance is very short as its in a lab right now.