Stuck flashing a working program to Minew nRF52832 Module MS50SFA-1Y32AI

I am trying to flash a simple program to toggle every 5 sec the voltage level of pin P0.27 of a Minew nRF52832 Module MS50SFA-1Y32AI (https://www.rutronik24.com/product/minew/ms50sfa-1y32ait/12797351.html).

I use the on-board ST-Link/V2.1 of a Nucleo MB1136 C-03.

My config options in the PlatformIO project are:

[env:adafruit_feather_nrf52832]
platform = nordicnrf52
board = adafruit_feather_nrf52832
framework = arduino
upload_protocol = stlink

“Upload” gives success, although with several messages in yellow:

CURRENT: upload_protocol = stlink
Uploading .pio/build/adafruit_feather_nrf52832/firmware_signature.bin
xPack Open On-Chip Debugger 0.12.0-01004-g9ea7f3d64-dirty (2023-01-30-15:03)
Licensed under GNU GPL v2
For bug reports, read
OpenOCD: Bug Reporting
debug_level: 1

0x4000

nRF52 device has a CTRL-AP dedicated to recover the device from AP lock.
A high level adapter (like a ST-Link) you are currently using cannot access
the CTRL-AP so ‘nrf52_recover’ command will not work.
Do not enable UICR APPROTECT.

[nrf52.cpu] halted due to debug-request, current mode: Thread
xPSR: 00000000 pc: 0x0000bcee msp: 00000000
** Programming Started **
Warn : Adding extra erase range, 0x00000020 … 0x00000fff
** Programming Finished **
** Verify Started **
** Verified OK **
** Resetting Target **
shutdown command invoked
=========================================================== [SUCCESS] Took 0.71 seconds ===========================================================

However, the voltage level of pin 0.27 never toggles: stays LOW, and never goes to HIGH.

My program is:

#include <Arduino.h>

#define PIN_TEST ( 27 )

void setup ( void ) {

pinMode ( PIN_TEST, OUTPUT ) ;

}

void loop ( void ) {

digitalWrite ( PIN_TEST, HIGH ) ;

delay ( 5000 ) ;

digitalWrite ( PIN_TEST, LOW ) ;

delay ( 5000 ) ;

}

I don’t know what exactly I am doing wrong, hence I wanted to ask for help.
Thanks in advance