The Customer has a package to deploy and when endpoints try downloading it, they're presented with "no package sources" and the download just keeps "retrying".
These client machines report to a Child SMP in a Hierarchy. There are multiple package servers that have the package ready reporting to that Child SMP but any of them belongs to the same Site as the client machines.
The Site in which the child SMP resides was missing Site Servers with package services installed. The SMP logs were also indicating this problem.
Because the Site that contains the child SMP does not have a site server with package services assigned to it, it caused that the proper codebases were not generated:
In a Hierarchy, it is very important to have a package server on the same Site as the SMP. Both Parent and Child SMPs need to have a package server (site server with package services installed) on their Site. See KB 184143 "Why we have the requirement to always have a Package Server for each SMP in a Hierarchy? Can we work without it?"