Okay.... so they *are* pulling the tftp download...
Do you have remote logging enabled on your provisioner syslogd? If you do allow remote access, nodes will log to the provisioner once they have their NIC up.
Set DEBUG on the nodes to a value of 3 or more (I... honestly don't remember if we ever exposed this in wwsh or if it's a `wwsh object modify` thing). This will start a debug shell after it tries bringing up the NIC and before it gets into the core of the provisioning. syslog isn't started yet, but if it did detect the NIC, there should be a /tmp/wwdev file.
Look under /sys/class/net/ for the network devices that are being detected. You should be able to check dmesg, etc... and do normal poking around. You'll be in a busybox shell.