When you create and delete preboot environments we store information about the environment in the database. Once you have done this more then 15 times it seems we have issues trying to recreate with the new options, even if you only have three options. You will notice those three options may not show for all site servers, and will not be in a ready state.
No error message, you will just not see the newly created option come up on the PXE menu.
The SQL database stores all menu instances even after they have been deleted. And if you have more then 15 instances we fail to build out the new instances on the servers.
Give it a couple of hours to finish the rebuild process and you will see the menu generate successfully.