Unfortunately Burn has a defect which leads to not showing embedded UI even when DisplayInternalUI is set to true.
The issue is logged (https://github.com/wixtoolset/issues/issues/4918/) and WiX team scheduled fixing the issue 4918/4921 for WiX v4.0.
This is unfortunate as there seems to be no any work around and building a custom bootstrapper UI (BA) seems to be the only available option for now.
The issue is logged (https://github.com/wixtoolset/issues/issues/4918/) and WiX team scheduled fixing the issue 4918/4921 for WiX v4.0.
This is unfortunate as there seems to be no any work around and building a custom bootstrapper UI (BA) seems to be the only available option for now.