RockPi 4c+ - NVME not recognized when booting from eMMC

Hi all,
my RockPi 4c+ arrived yesterday, yippieh.
Installed official Ubuntu 20.04 image to SD card. Everything fine, lsblk shows eMMC and NVME (Kioxia bg4 256GB). Wrote image to eMMC via dd, booting is okay, but NVME is not shown anymore via lsblk.
Does anybody had similar issues?
Thx in advance

What does dmesg | grep pcie show? Maybe you should use a higher current 5V power adapter?