u-boot saveenv to redundant fat does not persist env

[Pierre-Alexis Ciavaldini]

Hi,

I'm trying to integrate u-boot in our project that is a custom scripted build without yocto, for use with mender.
The complete discussion can be found here : https://hub.mender.io/t/pi3-usb-boot-support/595/54?u=peac
The problem is that when issuing saveenv in u-boot, it responds with "Saving Environment to FAT... OK" but then using fw_printenv in the booted linux, does not show saved variables.

The system currently boots because i've tricked it by getting the compiled-in env over uart (env print -a) and made a uboot.env using mkenvimage manually to enable fw_printenv to work.
I've noticed that when deleting "/boot/u-boot/uboot.env", u-boot's saveenv does not re-create it, so it seems to me that saveenv does not write uboot.env.
Here's the complete project files : https://git.iostud.io/cosmos/u-boot/-/tree/cosmos
relevant modified files are:
- configs/rpi_4_32b_defconfig
- include/config_mender_defines.h
- include/env_mender.h
- include/configs/rpi.h
- include/env_default.h
- include/config_mender.h

Any help or investigating direction would be greatly appreciated.
Thank you,
Pierre-Alexis Ciavaldini