Python box_dimensioner demo not working (SR300 or L515)

I'd like to try the box dimensioner example to evaluate Realsense devices, using the Python wrapper.

i.e. this example code.

https://github.com/IntelRealSense/librealsense/blob/development/wrappers/python/examples/box_dimensioner_multicam/box_dimensioner_multicam_demo.py

Unfortunately I can't get this to work and would appreciate any support.

Realsense SDK is installed, openCV is installed, Python 3.6.9 is used.
A RealSense SR300 hardware unit is connected to USB3.0 interface.
The realsense-viewer binary works fine and successfully connects to the RealSense hardware.
The librealsense repository is cloned from GitHub, and the appropriate python example (as above) is run (python3). Doesn't work - so I edited it with different sensor modes, as below.

$ rs-enumerate-devices
Device info:
Name : Intel RealSense SR300
Serial Number : 610205005115
Firmware Version : 3.10.10.0
Physical Port : /sys/devices/pci0000:00/0000:00:14.0/usb2/2-3/2-3.1/2-3.1:1.2/video4linux/video2
[rest of the output snipped, for brevity]

Stream Profiles supported by Coded-Light Depth Sensor
Supported modes:
stream resolution fps format
Infrared 1 640x480 @ 60Hz Y16
Infrared 1 640x480 @ 60Hz Y8
Infrared 1 640x240 @ 10Hz Y16
Depth 640x480 @ 60Hz Z16
Depth 640x480 @ 30Hz Z16
Depth 640x480 @ 10Hz Z16
Color 640x480 @ 10Hz RGB8
Color 640x480 @ 10Hz Y16
Color 640x480 @ 10Hz BGRA8

[I've snipped off most of the list of supported modes, for brevity]

The following modes are supported, so I'll choose the following. I figure that a conservative, low resolution and low frame rate gives the best chance of success.

Depth camera: 640x480, Z16, 10Hz
IR sensor: 640x480, Y8, 10Hz
RGB sensor: 640x480, Y16, 10Hz

Based on this enumeration supported modes on this hardware, I've edited the box_dimensioner_multicam_demo.py file as follows. (Sorry, not sure if we have code-formatting tags supported here.)

# Enable the streams from all the intel realsense devices
rs_config = rs.config()
rs_config.enable_stream(rs.stream.depth, 640, 480, rs.format.z16, 10)
rs_config.enable_stream(rs.stream.infrared, 640, 480, rs.format.y8, 10)
rs_config.enable_stream(rs.stream.color, 640, 480, rs.format.y16, 10)

This fails with a "RuntimeError: object doesn't support option #18" error.

$ ./box_dimensioner_multicam_demo.py
1 devices have been found
Traceback (most recent call last):
File "./box_dimensioner_multicam_demo.py", line 144, in <module>
run_demo()
File "./box_dimensioner_multicam_demo.py", line 49, in run_demo
device_manager.enable_all_devices()
File "/home/dev/librealsense/wrappers/python/examples/box_dimensioner_multicam/realsense_device_manager.py", line 167, in enable_all_devices
self.enable_device(serial, enable_ir_emitter)
File "/home/dev/librealsense/wrappers/python/examples/box_dimensioner_multicam/realsense_device_manager.py", line 156, in enable_device
sensor.set_option(rs.option.emitter_enabled, 1 if enable_ir_emitter else 0)
RuntimeError: object doesn't support option #18


I've also got a L515 LiDAR device, so I also wanted to try the same example on the L515 hardware. Again, the hardware is connected to USB3, and the realsense-viewer works fine and detects the device.

$rs-enumerate-devices
Device info:
Name : Intel RealSense L515
Serial Number : 00000000f0090002
Firmware Version : 01.04.01.00
Recommended Firmware Version : 01.04.01.00
Physical Port : /sys/devices/pci0000:00/0000:00:14.0/usb2/2-3/2-3:1.0/video4linux/video0
[Rest of information snipped.]

Looking at the supported sensor resolutions and modes, we have IR 640x480, Y8 30Hz, Depth sensor 640x480, Z16 30Hz, and RGB 1280x720, Y16 6Hz. I've edited box_dimensioner_multicam_demo.py accordingly. (Again, I figure that a conservative, low resolution and low frame rate gives the best chance of success.)

rs_config = rs.config()
rs_config.enable_stream(rs.stream.depth, 640, 480, rs.format.z16, 30)
rs_config.enable_stream(rs.stream.infrared, 640, 480, rs.format.y8, 30)
rs_config.enable_stream(rs.stream.color, 1280, 720, rs.format.y16, 6)

$ ./box_dimensioner_multicam_demo.py
1 devices have been found
Traceback (most recent call last):
File "./box_dimensioner_multicam_demo.py", line 144, in <module>
run_demo()
File "./box_dimensioner_multicam_demo.py", line 49, in run_demo
device_manager.enable_all_devices()
File "/home/dev/librealsense/wrappers/python/examples/box_dimensioner_multicam/realsense_device_manager.py", line 167, in enable_all_devices
self.enable_device(serial, enable_ir_emitter)
File "/home/dev/librealsense/wrappers/python/examples/box_dimensioner_multicam/realsense_device_manager.py", line 156, in enable_device
sensor.set_option(rs.option.emitter_enabled, 1 if enable_ir_emitter else 0)
RuntimeError: object doesn't support option #18

Again, I get the same kind of error.

Any advice or suggestions on how to fix this would be appreciated.