Cannot debug Seeeduino

I am using Visual Studio Code with the official PlatformIO extensions.
I can successfully Build and Upload to my Seeduino (seeedstudio.com/Seeeduino-V4.2-p-2517.html).
But, I cannot debug my Seeeduino board. Error in the DEBUG CONSOLE in the IDE is:

undefinedError: Currently, PlatformIO does not support debugging for seeeduino.
Please mail contact@pioplus.com or visit Redirecting...

So, the link Debugging — PlatformIO latest documentation states (Note Seeeduino absence):

ID		Name		Platform	Debug	Microcontroller	Frequency	Flash	RAM
seeedArchBLE	Seeed Arch BLE	Nordic nRF51	CMSIS-DAP (on-board)	NRF51822	16 MHz	128 Kb	16 Kb
seeedArchLink	Seeed Arch Link	Nordic nRF51	CMSIS-DAP (on-board)	NRF51822	16 MHz	256 Kb	16 Kb
seeedArchMax	Seeed Arch Max	ST STM32	Black Magic Probe, ST-LINK/V2-1 (on-board)	STM32F407VET6	168 MHz	512 Kb	192 Kb
seeedArchPro	Seeed Arch Pro	NXP LPC	CMSIS-DAP (on-board)	LPC1768	96 MHz	512 Kb	64 Kb
seeedTinyBLE	Seeed Tiny BLE	Nordic nRF51	CMSIS-DAP (on-board)

Whereas the board is officially supported:
Atmel AVR — PlatformIO latest documentation but clearly shows no Debug support.

ID		       Name		Platform	     Debug	Microcontroller	Frequency	Flash	RAM
seeeduino	Seeeduino	Atmel AVR	 	        ATMEGA328P	        16 MHz	        32 Kb	2 Kb

==========PROJECT DETAILS=============
[PLATFORMIO INI]
platformio.ini contains:

[platformio]
env_default = seeeduino

[env:uno]
platform = atmelavr
framework = arduino
board = uno

[env:seeeduino]
platform = atmelavr
board = seeeduino
framework = arduino

I get exactly the same results (shown below in detail) if I specify env_default=uno

How to proceed ?

For those interested in my environment and project details …

==========INSTALLATION DETAILS=============
Environment:

Distributor ID:	Ubuntu
Description:	Ubuntu 16.04.3 LTS
Release:	16.04
Codename:	xenial

Platformio Version:

platformio --version
PlatformIO, version 3.5.0

I added my user to the dialout group:
sudo usermod -a -G dialout my_username
so that I have access to the /dev/ttyACM* (* = 1 or 2 typically)

==========UDEV RULES=============
I previously had 98-openocd-udev.rules, but removed this when I added 99-platformio-udev.rules

99 rules installed as per:
sudo cp 99-platformio-udev.rules /etc/udev/rules.d/99-platformio-udev.rules

[Platformio Upload Task excutes successfully with warning:]

Warning! Please install `99-platformio-udev.rules` and check that your board's PID and VID are listed in the rules.
https://raw.githubusercontent.com/platformio/platformio/develop/scripts/99-platformio-udev.rules
Auto-detected: /dev/ttyACM1
Uploading .pioenvs/seeeduino/firmware.hex

avrdude: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.00s

avrdude: Device signature = 0x1e950f (probably m328p)
avrdude: reading input file ".pioenvs/seeeduino/firmware.hex"
avrdude: writing flash (9576 bytes):

Writing | ################################################## | 100% 1.54s

avrdude: 9576 bytes of flash written
avrdude: verifying flash memory against .pioenvs/seeeduino/firmware.hex:
avrdude: load data flash data from input file .pioenvs/seeeduino/firmware.hex:
avrdude: input file .pioenvs/seeeduino/firmware.hex contains 9576 bytes
avrdude: reading on-chip flash data:

Reading | ################################################## | 100% 1.23s

avrdude: verifying ...
avrdude: 9576 bytes of flash verified

avrdude: safemode: Fuses OK (E:00, H:00, L:00)

avrdude done.  Thank you.

========================================================================= [SUCCESS] Took 5.00 seconds =========================================================================

================================================================================== [SUMMARY] ==================================================================================
Environment uno                 [SKIP]
Environment nodemcu             [SKIP]
Environment teensy31            [SKIP]
Environment lpmsp430g2553       [SKIP]
Environment seeeduino           [SUCCESS]
========================================================================= [SUCCESS] Took 5.00 seconds =========================================================================

Terminal will be reused by tasks, press any key to close it.

Is anybody else trying to debug a Seeeduino ?

We don’t currently support debugging for AVR platform. Stay tuned with us on https://twitter.com/PlatformIO_Org