Custom Julia system image

I am trying to create a system image for a specific project (Project.toml) using python -m julia.sysimage

  1. How can I enforce those packages to be part of the system image?
  2. If the system image has only PyCall and Precompile why do I get this error?
ERROR: The following 2 direct dependencies failed to precompile:
JuMP [4076af6c-e467-56ae-b986-b466b2749572]
Error: Missing source file for JuMP [4076af6c-e467-56ae-b986-b466b2749572]
MosekTools [1ec41992-ff65-5c91-ac43-2df89e9693a4]
Error: Missing source file for MosekTools [1ec41992-ff65-5c91-ac43-2df89e9693a4]