More, this is on a Lenovo laptop, LCD only (no external monitors, no USB graphics cards on anything like that). Also:

=================

$ openscad --info
QObject::startTimer: Timers can only be used with threads started with QThread
OpenSCAD Version: 2021.01
System information: Linux 5.11.0-18-generic #19-Ubuntu SMP Fri May 7 14:22:03 UTC 2021 x86_64 Ubuntu 21.04 4 CPUs 7.23 GB RAM
User Agent: OpenSCAD/2021.01 (Linux x86_64; Ubuntu 21.04)
Compiler: GCC "10.2.1 20210306" 64bit
MinGW build: No
Debug build: No
Boost version: 1_74
Eigen version: 3.3.9
CGAL version, kernels: 5.2, Cartesian<Gmpq>, Extended_cartesian<Gmpq>, Epeck
OpenCSG version: OpenCSG 1.4.2
Qt version: 5.15.2
QScintilla version: 2.11.6
InputDrivers: 
GLib version: 2.67.5
lodepng version: 20180910
libzip version: 1.7.3
fontconfig version: 2.13.1
freetype version: 2.10.4
harfbuzz version: 2.7.4
cairo version: 1.16.0
lib3mf version: 1.8.1
Application Path: /usr/bin
Documents Path: /home/rob/.local/share
User Documents Path: /home/rob/Documents
Resource Path: /usr/share/openscad
User Library Path: /home/rob/.local/share/OpenSCAD/libraries
User Config Path: /home/rob/.config/OpenSCAD
Backup Path: /home/rob/.local/share/OpenSCAD/backups
OPENSCADPATH: <not set>
OpenSCAD library path:
  /home/rob/.local/share/OpenSCAD/libraries
  /usr/share/openscad/libraries

OPENSCAD_FONT_PATH: <not set>
OpenSCAD font path:
  /usr/share/fonts
  /usr/local/share/fonts
  /home/rob/.local/share/fonts
  /home/rob/.fonts
  /usr/share/fonts/X11
  /usr/share/fonts/cMap
  /usr/share/fonts/cmap
  /usr/share/fonts/opentype
  /usr/share/fonts/truetype
  /usr/share/fonts/type1
  /usr/share/fonts/X11/Type1
  /usr/share/fonts/X11/encodings
  /usr/share/fonts/X11/misc
  /usr/share/fonts/X11/util
  /usr/share/fonts/cmap/adobe-cns1
  /usr/share/fonts/cmap/adobe-gb1
  /usr/share/fonts/cmap/adobe-japan1
  /usr/share/fonts/cmap/adobe-japan2
  /usr/share/fonts/cmap/adobe-korea1
  /usr/share/fonts/opentype/font-awesome
  /usr/share/fonts/opentype/freefont
  /usr/share/fonts/opentype/malayalam
  /usr/share/fonts/opentype/noto
  /usr/share/fonts/opentype/urw-base35
  /usr/share/fonts/truetype/Gargi
  /usr/share/fonts/truetype/Gubbi
  /usr/share/fonts/truetype/Nakula
  /usr/share/fonts/truetype/Navilu
  /usr/share/fonts/truetype/Sahadeva
  /usr/share/fonts/truetype/Sarai
  /usr/share/fonts/truetype/abyssinica
  /usr/share/fonts/truetype/arphic
  /usr/share/fonts/truetype/dejavu
  /usr/share/fonts/truetype/droid
  /usr/share/fonts/truetype/font-awesome
  /usr/share/fonts/truetype/fonts-beng-extra
  /usr/share/fonts/truetype/fonts-deva-extra
  /usr/share/fonts/truetype/fonts-gujr-extra
  /usr/share/fonts/truetype/fonts-guru-extra
  /usr/share/fonts/truetype/fonts-kalapi
  /usr/share/fonts/truetype/fonts-orya-extra
  /usr/share/fonts/truetype/fonts-telu-extra
  /usr/share/fonts/truetype/fonts-yrsa-rasa
  /usr/share/fonts/truetype/freefont
  /usr/share/fonts/truetype/kacst
  /usr/share/fonts/truetype/kacst-one
  /usr/share/fonts/truetype/lao
  /usr/share/fonts/truetype/lato
  /usr/share/fonts/truetype/liberation
  /usr/share/fonts/truetype/liberation2
  /usr/share/fonts/truetype/libreoffice
  /usr/share/fonts/truetype/lohit-assamese
  /usr/share/fonts/truetype/lohit-bengali
  /usr/share/fonts/truetype/lohit-devanagari
  /usr/share/fonts/truetype/lohit-gujarati
  /usr/share/fonts/truetype/lohit-kannada
  /usr/share/fonts/truetype/lohit-malayalam
  /usr/share/fonts/truetype/lohit-oriya
  /usr/share/fonts/truetype/lohit-punjabi
  /usr/share/fonts/truetype/lohit-tamil
  /usr/share/fonts/truetype/lohit-tamil-classical
  /usr/share/fonts/truetype/lohit-telugu
  /usr/share/fonts/truetype/lyx
  /usr/share/fonts/truetype/malayalam
  /usr/share/fonts/truetype/noto
  /usr/share/fonts/truetype/open-sans
  /usr/share/fonts/truetype/padauk
  /usr/share/fonts/truetype/pagul
  /usr/share/fonts/truetype/samyak
  /usr/share/fonts/truetype/samyak-fonts
  /usr/share/fonts/truetype/sinhala
  /usr/share/fonts/truetype/teluguvijayam
  /usr/share/fonts/truetype/tibetan-machine
  /usr/share/fonts/truetype/tlwg
  /usr/share/fonts/truetype/ttf-bitstream-vera
  /usr/share/fonts/truetype/ttf-khmeros-core
  /usr/share/fonts/truetype/ubuntu
  /usr/share/fonts/type1/gsfonts
  /usr/share/fonts/type1/urw-base35
  /usr/share/fonts/X11/encodings/large


GLEW version: 2.1.0
OpenGL Version: 4.6 (Compatibility Profile) Mesa 21.0.1
GL Renderer: AMD Radeon R7 Graphics (CARRIZO, DRM 3.40.0, 5.11.0-18-generic, LLVM 11.0.1)
GL Vendor: AMD
RGBA(8888), depth(24), stencil(8)
GL_ARB_framebuffer_object: yes
GL_EXT_framebuffer_object: yes
GL_EXT_packed_depth_stencil: yes
GL context creator: GLX
PNG generator: lodepng
GLX version: 1.4
OS info: Linux 5.11.0-18-generic #19-Ubuntu SMP Fri May 7 14:22:03 UTC 2021
Machine: x86_64

================

Thanks again!