I assume you are talking about “ssh-copy-id”. If possible, please post the command used and the output of the copy-id failure.
FYI, on the Jetson you could delete the “~nvidia/.ssh/authorized_keys” to remove current key knowledge and start over on keys. You could delete the “~nvidia/.ssh/known_hosts” to further remove knowledge of previous ssh allows.
You may want to further test with scp since this is how copies are done. Example from host (replace “x2” with the IP address of your TX2):
echo "testing" > deleteme.txt
scp deleteme.txt nvidia@x2:/home/nvidia/Downloads
scp nvidia@x2:/home/nvidia/Downloads/deleteme.txt .
I don’t know for certain, but perhaps root on your host is at times doing the scp. So try the above with “sudo” as well. You can run “sudo -s” to drop into an sudo shell and stay root, do all of the above testing again, and then type “exit” to leave the sudo shell. For root directories would be “/root/.ssh/” instead of “/home/nvidia/.ssh/”.