Add collaborator not working

Hi everyone,
when trying to add a collaborator to a private repository by user name via the search field, the user appears as search result but when clicking on it the view switches to a text field with “user/(user number)” so that it’s impossible to add it. Tested in two browsers based on different rendering engines. Is this a temporary issue that’s known to happen every once in a while or am I doing something wrong? Is there a workaround?
Thanks, Matthias

let us wait and see whether this is an on-going issue by now, maybe it’s related to this one

Seems to be a temporary issue. It failed multiple times in a row for me but after waiting 30 mins eventually the search result stayed in view as expected.