Development tools for Zephyr on STM32Workbench for Zephyr: VS Code extension to set up, build, flash and debug Zephyr applications on STM32.Devicetree manager: browse, edit and visualize Zephyr devicetree, STM32CubeMX-like for Zephyr.
In the .cproject I removed every folderInfo block where the resourcePath was set to one of the directories which wasn't picking up the change to 'hard'. It compliles now.