fw_setenv boot_targets not working as expected with image 1.2.1

root@iot2050:~# fw_setenv boot_targets mmc0 usb0

root@iot2050:~# fw_printenv boot_targets

boot_targets=mmc0 usb0

root@iot2050:~# fw_setenv boot_targets mmc0 usb0

root@iot2050:~# fw_printenv boot_targets

boot_targets=mmc0

if i remove the sd-card, the iot2050 will not boot from usb0

any hints/advises very appreciated

Urs

btw, tested on basic IoT2050s

UPDATE

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workaround: i booted with image 1.1.1 and could successfully set the boot_targets so i've a plan B when sd-card with 1.2.1 is not booting anymore

UPDATE 2

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thx to jan-k, the solution with image 1.2.1

fw_setenv boot_targets 'mmc0 usb0'

i like syntax changes.... sarkasm off