Tools > Options > nRF Connect > Additional CMake Options -DCONF_FILE=prj_release.conf

File > Open nRF Connect SDK Project... to re-open the project

I tried to do the above with and without selecting a 'Clean Build Directory'?

In both cases I see in SES logs that prj_debug.conf is being merged instead of prj_release.conf as specified in -DCONF_FILE=prj_release.conf. See logs below.
Can someone please enlighten me and tell me what I am doing wrong.

Creating solution HomeBeacon_dev_sb.emProject                                    C:/Zypher/v1.7.0/toolchain/opt/bin/cmake.exe -GNinja -DBOARD=nrf52833dk_nrf52833 -DBOARD_DIR=C:\Zypher\v1.7.0\zephyr\boards\arm\nrf52833dk_nrf52833 -BC:\Sandbox\HomeBeacon_dev_sb\build_nrf52833dk_nrf52833_rel_v1_3_99 -SC:\Sandbox\HomeBeacon_dev_sb -DNCS_TOOLCHAIN_VERSION=1.7.0 -DCONF_FILE=prj_release.conf -DDTC_OVERLAY_FILE=C:/Sandbox/HomeBeacon_dev_sb/nrf52833dk_nrf52833.overlay -DEXTRA_KCONFIG_TARGETS=menuconfig_ses -DEXTRA_KCONFIG_TARGET_COMMAND_FOR_menuconfig_ses=C:\Zypher\v1.7.0\toolchain\segger_embedded_studio/html/configure_nordic_project_menuconfig.py
-- Application: C:/Sandbox/HomeBeacon_dev_sb
-- Zephyr version: 2.6.99 (C:/Zypher/v1.7.0/zephyr), build: v2.6.99-ncs1
-- Found Python3: C:/Zypher/v1.7.0/toolchain/opt/bin/python.exe (found suitable exact version "3.8.2") found components: Interpreter
-- Found west (found suitable version "0.11.1", minimum required is "0.7.1")
-- Board: nrf52833dk_nrf52833
-- Cache files will be written to: C:/Zypher/v1.7.0/zephyr/.cache
-- Found dtc: C:/Zypher/v1.7.0/toolchain/opt/bin/dtc.exe (found suitable version "1.4.7", minimum required is "1.4.6")
-- Found toolchain: gnuarmemb (C:/Zypher/v1.7.0/toolchain/opt)
-- Found BOARD.dts: C:/Zypher/v1.7.0/zephyr/boards/arm/nrf52833dk_nrf52833/nrf52833dk_nrf52833.dts
-- Found devicetree overlay: C:/Sandbox/HomeBeacon_dev_sb/nrf52833dk_nrf52833.overlay
-- Generated zephyr.dts: C:/Sandbox/HomeBeacon_dev_sb/build_nrf52833dk_nrf52833_rel_v1_3_99/zephyr/zephyr.dts
-- Generated devicetree_unfixed.h: C:/Sandbox/HomeBeacon_dev_sb/build_nrf52833dk_nrf52833_rel_v1_3_99/zephyr/include/generated/devicetree_unfixed.h
-- Generated device_extern.h: C:/Sandbox/HomeBeacon_dev_sb/build_nrf52833dk_nrf52833_rel_v1_3_99/zephyr/include/generated/device_extern.h
-- Including generated dts.cmake file: C:/Sandbox/HomeBeacon_dev_sb/build_nrf52833dk_nrf52833_rel_v1_3_99/zephyr/dts.cmake
Parsing C:/Sandbox/HomeBeacon_dev_sb/Kconfig
Loaded configuration 'C:/Zypher/v1.7.0/zephyr/boards/arm/nrf52833dk_nrf52833/nrf52833dk_nrf52833_defconfig'
Merged configuration 'C:/Sandbox/HomeBeacon_dev_sb/prj_debug.conf'
Configuration saved to 'C:/Sandbox/HomeBeacon_dev_sb/build_nrf52833dk_nrf52833_rel_v1_3_99/zephyr/.config'
Kconfig header saved to 'C:/Sandbox/HomeBeacon_dev_sb/build_nrf52833dk_nrf52833_rel_v1_3_99/zephyr/include/generated/autoconf.h'

...

Also, what is the difference between re-opening and re-loading a project in Segger Embedded Studio (SES-NE)?

Thank you.

Kind regards