Altium board import of footprint references broken

Description

Importing an Altium board in Pcbnew results in all footprint references to be set to "UNK". This does not happen in 8.0.3. Due to the number of build errors in the 8.0 branch, I could only pair down the offending commits using git bisect to b589da63 or 48077d77. I suspect the guilty commit is b589da63 but reverting it results in a broken build so testing it will require manually removing the offending commit. I suspect this issue is Altium board file version dependent because the QA Altium test board appears to import the references correctly. The Altium board file in issue #18156 demonstrates the issue.

Steps to reproduce

1. Open Pcbnew in stand alone mode.
2. Run File->Import->Non-KiCad Board File..." and select the Altium board file provided in issue #18156.
3. Observe all references are set to "UNK".

KiCad Version

Application: KiCad PCB Editor x86_64 on x86_64

Version: 8.0.4-62-g5c89937870, debug build

Libraries:
	wxWidgets 3.2.4
	FreeType 2.13.2
	HarfBuzz 8.3.0
	FontConfig 2.15.0
	libcurl/8.5.0 GnuTLS/3.8.3 zlib/1.3 brotli/1.1.0 zstd/1.5.5 libidn2/2.3.7 libpsl/0.21.2 (+libidn2/2.3.7) libssh/0.10.6/openssl/zlib nghttp2/1.59.0 librtmp/2.3 OpenLDAP/2.6.7

Platform: Ubuntu 24.04 LTS, 64 bit, Little endian, wxGTK, X11, ubuntu, x11
OpenGL: AMD, AMD Radeon Graphics (radeonsi, raphael_mendocino, LLVM 17.0.6, DRM 3.57, 6.8.0-39-generic), 4.6 (Compatibility Profile) Mesa 24.0.9-0ubuntu0.1

Build Info:
	Date: Aug  6 2024 11:48:50
	wxWidgets: 3.2.4 (wchar_t,wx containers) GTK+ 3.24
	Boost: 1.83.0
	OCC: 7.6.3
	Curl: 8.5.0
	ngspice: 42
	Compiler: GCC 13.2.0 with C++ ABI 1018

Build settings:
	KICAD_STDLIB_DEBUG=OFF
	KICAD_STDLIB_LIGHT_DEBUG=OFF
	KICAD_SANITIZE_ADDRESS=OFF
	KICAD_SANITIZE_THREADS=OFF