3D viewer not showing some .step models.

Description

-Current behavior: See attached project: the component on the board is not shown in 3d viewer, while it is shown correctly in the "footprint properties" dialog.

-Expected behavior: same behavior in dialog and viewer: the model should appear in both.

Steps to reproduce

1. Open the attached project 3dViewer.zip
2. select U1 and edit (E shortcut), see "3D models" tab: the 3D model of the component shows correctly.
3. Close the dialog and open the 3D viewer: on the board the 3d model is missing.

Notes:

-It happens only on some .step files (as for the one included in the attached project, made with FreeCad).

-If the board is exported as a step file, the 3d model is NOT missing (works correctly).

-No errors or warning about this are shown, even in the terminal used to run kicad.

KiCad Version

Application: KiCad

Version: (5.99.0-12071-g0463fc4c2b), release build

Libraries:
	wxWidgets 3.1.5
	libcurl/7.64.0 GnuTLS/3.6.7 zlib/1.2.11 libidn2/2.0.5 libpsl/0.20.2 (+libidn2/2.0.5) libssh2/1.8.0 nghttp2/1.36.0 librtmp/2.3

Platform: Linux 4.19.0-17-amd64 x86_64, 64 bit, Little endian, wxGTK, gnome, x11

Build Info:
	Date: Aug 24 2021 08:57:12
	wxWidgets: 3.1.5 (wchar_t,wx containers) GTK+ 3.24
	Boost: 1.69.0
	OCE: 6.9.1
	Curl: 7.64.0
	ngspice: 32+
	Compiler: GCC 8.3.0 with C++ ABI 1013

Build settings:
	KICAD_USE_OCE=ON
	KICAD_USE_EGL=ON
	KICAD_SPICE=ON