PCBNew: Import configuration from another PCB does not correctly import PCB layer stackup

Description

When importing the configuration of a 4-layer PCB (Created with v5.x, but edited and saved with v6.x) in the configurations dialog, the layer stackup is broken. Both inner layers are imported but the number of layers remains 2. You can change the number of layers to 4 manually, but the thicknesses of each layer do not match the imported PCB. See attached screenshots. Source PCB:

To_be_imported

Destination PCB after importing:

After_import

Steps to reproduce

  1. Create new Project
  2. Open PCB configuration dialog
  3. Import settings from another PCB
  4. Select the board file (4-layer PCB)
  5. Select all import options

KiCad Version

Application: KiCad Leiterplatteneditor

Version: 6.0.4-6f826c9f35~116~ubuntu22.04.1, release build

Libraries:
	wxWidgets 3.0.5
	libcurl/7.81.0 OpenSSL/3.0.2 zlib/1.2.11 brotli/1.0.9 zstd/1.4.8 libidn2/2.3.2 libpsl/0.21.0 (+libidn2/2.3.2) libssh/0.9.6/openssl/zlib nghttp2/1.43.0 librtmp/2.3 OpenLDAP/2.5.11

Platform: Linux 5.15.0-27-generic x86_64, 64 bit, Little endian, wxGTK, KDE, x11

Build Info:
	Date: Mar 18 2022 15:49:19
	wxWidgets: 3.0.5 (wchar_t,wx containers,compatible with 2.8) GTK+ 3.24
	Boost: 1.74.0
	OCC: 7.5.2
	Curl: 7.81.0
	ngspice: 36
	Compiler: GCC 11.2.0 with C++ ABI 1016

Build settings:
	KICAD_USE_OCC=ON
	KICAD_SPICE=ON