From what i have found after setting everything up with administrator rights is when i start EFBv2 i see the traffic on the ground at whtever airport i choose , the traffic is in red, then i start P3Dv4 and the traffic dissapears from EFB, i start vpilot ans still no traffic on EFB even though i can see it on the ground in the sim, now i close EFB server and reopen it and viola the traffic reappears on EFB client. Dont know if this helps but it is the way it is working for me.
yours
Kevin