Ok, I solved it.
This was my .uproject module configuration:
"Modules":
{
"Name": "MyGame",
"Type": "Runtime",
"LoadingPhase": "Default",
"AdditionalDependencies":
"Engine",
"CoreUObject"
]
},
{
"Name": "MyGameEditorExtension",
"Type": "Editor",
"LoadingPhase": "PostEngineInit"
}
]
I have edited the type and the loading phase of my editor extension module:
"Modules":
{
"Name": "MyGame",
"Type": "Runtime",
"LoadingPhase": "Default",
"AdditionalDependencies":
"Engine",
"CoreUObject"
]
},
{
"Name": "MyGameEditorExtension",
"Type": "Runtime",
"LoadingPhase": "Default"
}
]