SSIS Project level Connection Managers and ExecuteOutOfProcess - not working

This question was asked by someone else before on this forum but it seems nobody could provide an answer:

I have a SSIS 2012 project with about 30 package and they are all using connection managers defined at the project level. These packages are all beeing run from a master package with Execute SQL tasks and the property ExecuteOutOfProcess = false.

However some of these packages are high volume and use a lot of ressources causing memory errors, so I would like to run these packages out of process. When I set the ExecuteOutOfProcess = true in the Execute SQL task, I get an error like this:

"Error: 0xC0022102 at Id_Frequency: Error 0x80010105 while executing package from project reference package "Id_Frequency.dtsx". The server threw an exception"

It seems to me that when beeing run out of process, the package does not see the project level connections.

Has anyone seen this before ?

Thank you very much,

Chris