Try to flash STM32 with openocd from Ubuntu console
I think you need to add the scripts directory in the openocd command.
The scripts are in ~/Ac6/SystemWorkbench/plugins/fr.ac6.mcu.debug.XXXXXXXXXXX/resources/openocd/st_scripts
> Ac6/SystemWorkbench/plugins/fr.ac6.mcu.externaltools.openocd.linux64_1.23.0.201904120827/tools/openocd/bin/openocd -f STM32Pro/F334R8Test/F334R8Test\ Run.cfg -s ~/Ac6/SystemWorkbench/plugins/fr.ac6.mcu.debug.XXXXXXXXXXX/resources/openocd/st_scripts -c “program STM32/F334R8Test/Debug/F334R8Test.elf verify reset exit”