Pio ignores custom partition / can't get build to use my custom partition

I am not sure if this is a bug, or if I am doing something wrong. Anyway, this one kept me busy for the entire day.
Whatever I try, pio keeps building partitions.bin using default.csv, despite the explicit override board_build.partition in platfomio.ini
I followed these instructons:
[Custom partitions](Espressif 32 — PlatformIO latest documentation)

The platformio.config:

platform = espressif32
board = esp32doit-devkit-v1
board_build.partition = mypartition.csv
framework = arduino
monitor_speed = 115200
monitor_filters = esp32_exception_decoder
upload_speed = 921600
check_skip_packages = yes
lib_deps = 
	lennarthennigs/ESP Telnet@^2.0.0
build_type = debug

the partitions file is in the project folder root , next to platformio.ini
Build verbose shows:

Processing esp32doit-devkit-v1 (platform: espressif32; board: esp32doit-devkit-v1; board_build.partition: mypartition.csv; framework: arduino; monitor_speed: 115200; monitor_filters: esp32_exception_decoder; upload_speed: 921600; check_skip_packages: True; lib_deps: bblanchon/ArduinoJson@^6.20.0, ayushsharma82/AsyncElegantOTA@^2.2.7, rlogiacco/CircularBuffer@^1.3.3, lennarthennigs/ESP Telnet@^2.0.0, jonniezg/EWMA@^1.0.2, luisllamasbinaburo/MedianFilterLib@^1.0.0, me-no-dev/AsyncTCP@^1.1.1, https://github.com/me-no-dev/ESPAsyncWebServer.git; build_type: debug)
CONFIGURATION: https://docs.platformio.org/page/boards/espressif32/esp32doit-devkit-v1.html
PLATFORM: Espressif 32 (5.3.0) > DOIT ESP32 DEVKIT V1
HARDWARE: ESP32 240MHz, 320KB RAM, 4MB Flash
DEBUG: Current (cmsis-dap) External (cmsis-dap, esp-bridge, esp-prog, iot-bus-jtag, jlink, minimodule, olimex-arm-usb-ocd, olimex-arm-usb-ocd-h, olimex-arm-usb-tiny-h, olimex-jtag-tiny, tumpa)
 - framework-arduinoespressif32 @ 3.20006.221224 (2.0.6) 
 - tool-esptoolpy @ 1.40400.0 (4.4.0) 
 - toolchain-xtensa-esp32 @ 8.4.0+2021r2-patch5

and then further down the line:

"C:\Users\michi\.platformio\penv\Scripts\python.exe" "C:\Users\michi\.platformio\packages\tool-esptoolpy\esptool.py" --chip esp32 elf2image --flash_mode dio --flash_freq 40m --flash_size 4MB -o .pio\build\esp32doit-devkit-v1\bootloader.bin C:\Users\michi\.platformio\packages\framework-arduinoespressif32\tools\sdk\esp32\bin\bootloader_dio_40m.elf
"C:\Users\michi\.platformio\penv\Scripts\python.exe" "C:\Users\michi\.platformio\packages\framework-arduinoespressif32\tools\gen_esp32part.py" -q C:\Users\michi\.platformio\packages\framework-arduinoespressif32\tools\partitions\default.csv .pio\build\esp32doit-devkit-v1\partitions.bin
esptool.py v4.4
Creating esp32 image...
Merged 1 ELF section
Successfully created esp32 image.

It still uses default.csv.

Does anyone know what I am doing wrong / or what I need to do to fix this ?
Help much appreciated !

But the documentation says board_build.partitions, not board_build.partition?

Oh boy, missed that one, I look like an idiot …
And of course it works like a charm . :-
Lessons learned:

  • Don’t trust pio for checking platformio.ini on syntax or wrong variables
  • check, check and doublecheck before posting anything…
    Anyway, tx for your help!!