Hi,
I found this variable: nozzle_offsetting_for_disallowed_areas in printer definitions - so If you want to print in grayed out areas, you have to add this line to printer definition file (C:\Program Files\Ultimaker Cura 3.3\resources\definitions\) under "metadata" section:
"nozzle_offsetting_for_disallowed_areas" : false
example:
"metadata": {
"author": "Ultimaker",
"manufacturer": "Ultimaker B.V.",
"quality_definition": "ultimaker2",
"weight": 3,
"file_formats": "text/x-gcode",
"icon": "icon_ultimaker2.png",
"platform": "ultimaker2go_platform.obj",
"platform_texture": "Ultimaker2Gobackplate.png",
"platform_offset": [0, 0, 0],
"first_start_actions": [],
"supported_actions":["UpgradeFirmware"],
"has_materials": true,
"has_machine_quality": true,
"has_variants": true,
"nozzle_offsetting_for_disallowed_areas" : false,
"machine_extruder_trains":
{
"0": "ultimaker_2_go_dual_1",
"1": "ultimaker_2_go_dual_2"
}