Installing or updating TWRP on pollux

Trying to install TWRP with fastboot flash recovery twrp.img fails with an error like:

target didn't report max-download-size

followed by:

FAILED (remote: Command not allowed)

But it is possible to install TWRP it with a dd command.

adb root
adb push twrp-3.2.1-0-pollux.img
adb shell

dd if=/sdcard/twrp-3.2.1-0-pollux.img of=/dev/block/platform/msm_sdcc.1/by-name/FOTAKernel

References: