Currently pictures from an external URL (file directory on a web server) are only synched into Confluence, but NOT into LUP -- so the LUP profile shows a grey avatar, while Confluence shows the picture.
It would be a great improvement, if there is not the need to set-up a web server to link the pictures from there, but to synch them to LUP, i. e. onto the Confluence server and show them from there.