Based on guidance from several threads, I was finally able to get the vendors to phase correctly and interact with me. The steps I had to follow:
- Portal to SW
- Portal back to Panda
- Fly myself through VoEB
- Take path of wall to Vendors
- DO NOT cross into Dread Wastes, stay on VotFW side of wall
- Carefully edge toward PVP Vendor
After 30 hours of being unable to spend honor I was finally able to interact with them normally.