I hit this on a 13.1 box. I expect you found a workaround, but since it's not mentioned here, I'll add mine (for anyone else who searches on this issue)
You just need to add a path to the SCP command.
So instead of 'scp afile bigip:' use 'scp afile bigip:~' (for your home directory)
I know this is old but to help others, here is my workaround.
Rather than using: "scp file.ucs remoteserver:"
use the full path to the file you are sending "scp /var/local/ucs/file.ucs remoteserver:"
Do this even if current working path is in the same directory as the file.
I am having the problem using version 188.8.131.52 on Viprion "vCMP Guest", when I try drag and drop via "winscp", I recived this same error "relative addresses not allowed".
Workaround: To copy my files using winscp, I use right botton mouse > copy on file and rigth botton mouse > paste on my "desktop".
I hope that works with you too.