[U-Boot] U-Boot Tool: fw_setenv - kernel option?

After using a plain vanilla instead of a vendor kernel I do have problems with fw_setenv. Althoug fw_printenv still works fine, after usage of fw_setenv the environment is destroyed, CRC error.

I checked a lot of things, changed u-boot, devicetree, fw_setenv ... and finally came to the point, that it just depends on the kernel. Only changing the kernel makes the difference. I assume that there is an option not enabled. Honestly, I am lost with the differences - I couldn't identify the one that makes difference. Using an older config file, with lot more options, than it works also with a newer kernel.

Someone has an idea, which of the million settings is my friend? CONFIG_CRC16 and 32 are both enabled.

Best regards Arno