The same problem. fastboot devices works and shows a device, but no other “fastboot”. Almost “clean” Manjaro stable install.
Windows on the same pc, same cable and same phone works fine.
What’s more interesting that at first it worked ok on linux, but suddenly just stopped. Total mystery.
/data/nokia/magisk /data/nokia/magisk/fastboot boot magisk_patched-23000_oQ8tr.img 1 ✘ 1m 35s
Sending ‘boot.img’ (65536 KB)
some fastboot commands just don’t work, while it definitely works on the same machine (device, cable) on win.
/data/nokia/magisk fastboot set_active b 1 ✘
Setting current slot to ‘b’ FAILED (remote: ‘Invalid Slot’)
fastboot: error: Command failed