I was getting similar myself with the ipxe Rom hanging at “iPXE initializing devices”. The solution was to build a fresh undionly.kpxe (https://wiki.fogproject.org/wiki/index.php/IPXE#Compile).
Before you bake, modify general.h to comment out or remove the following lines:
#define DOWNLOAD_PROTO_HTTPS
#define IMAGE_TRUST_CMD
#define CERT_CMD
Then compile, and copy the rom to your tftp folder.

I was getting similar myself with the ipxe Rom hanging at “iPXE initializing devices”. The solution was to build a fresh undionly.kpxe (https://wiki.fogproject.org/wiki/index.php/IPXE#Compile).
Before you bake, modify general.h to comment out or remove the following lines:
#define DOWNLOAD_PROTO_HTTPS
#define IMAGE_TRUST_CMD
#define CERT_CMD
Then compile, and copy the rom to your tftp folder.