Applied materials are not saved

I apply a grass .rmtl (I downloaded to the library) to the ground plane and oak to an object sitting on the plane. Works good:

I save the .3dm with ‘save textures’ ticked, but on reopening, both applied materials are gone. However, there is a material in the list called "(unnamed) and when I click it, the grass returns to the ground plane and the object is black instead of Oak.

I have searched for something I need to do to save materials, but evidently it is expected to save when the whole file is saved.

Here is the small test file that I am able to repeat the issue:
Test4.3dm (2.1 MB)

I need an assist to figure out what I am doing wrong or more importantly, what I need to do to keep my materials on the objects I apply them to.

Thank you!

Best regards,
B


Material File from the Net:
physicallybased-grass.rmtl (788.1 KB)
Oak is just from the library.


Here is my SystemInfo:

Rhino 6 SR35 2021-8-10 (Rhino 6, 6.35.21222.17001,
License type: Educational, build 2021-08-10
License details: Stand-Alone

Windows 10.0.0 SR0.0 or greater (Physical RAM: 14Gb)
Machine name: AVA-548762-1

Computer platform: DESKTOP

Standard graphics configuration.
Primary display and OpenGL: AMD Radeon™ RX Vega 11 Graphics (AMD) Memory: 2GB, Driver date: 8-26-2021 (M-D-Y). OpenGL Ver: 4.6.14761 Compatibility Profile Context 21.30.14 30.0.13014.8
> Accelerated graphics device with 5 adapter port(s)
- Windows Main Display attached to adapter port #0

OpenGL Settings
Safe mode: Off
Use accelerated hardware modes: On
Redraw scene when viewports are exposed: On

Anti-alias mode: 4x
Mip Map Filtering: Linear
Anisotropic Filtering Mode: High

Vendor Name: ATI Technologies Inc.
Render version: 4.6
Shading Language: 4.60
Driver Date: 8-26-2021
Driver Version: 30.0.13014.8
Maximum Texture size: 16384 x 16384
Z-Buffer depth: 24 bits
Maximum Viewport size: 16384 x 16384
Total Video Memory: 2 GB

Rhino plugins
C:\Program Files\Rhino 6\Plug-ins\Commands.rhp “Commands” 6.35.21222.17001
C:\Program Files\Rhino 6\Plug-ins\rdk.rhp “Renderer Development Kit”
C:\Program Files\Rhino 6\Plug-ins\RhinoBonusTools.rhp “Rhino Bonus Tools”
C:\Program Files\Rhino 6\Plug-ins\RhinoRender.rhp “Rhino Render”
C:\Program Files\Rhino 6\Plug-ins\rdk_etoui.rhp “RDK_EtoUI” 6.35.21222.17001
C:\Program Files\Rhino 6\Plug-ins\rdk_ui.rhp “Renderer Development Kit UI”
C:\Program Files\Rhino 6\Plug-ins\NamedSnapshots.rhp “Snapshots”
C:\Program Files\Rhino 6\Plug-ins\RhinoCycles.rhp “RhinoCycles” 6.35.21222.17001
C:\Program Files\Rhino 6\Plug-ins\Toolbars\Toolbars.rhp “Toolbars” 6.35.21222.17001
C:\Program Files\Rhino 6\Plug-ins\3dxrhino.rhp “3Dconnexion 3D Mouse”
C:\Program Files\Rhino 6\Plug-ins\Displacement.rhp “Displacement”