Why do I get the error "There was an error retrieving new relatives"?
This error usually occurs only in people with a large number of matches at 23andMe (more than 2,000).
You are requesting something from 23andMe, they are prepared to provide what you asked for (in this example, a list of your matching segments). Whilst waiting, you feel it is taking too long and walk away rather than pick up the item.
A timeout period occurs, and the best way to counter it is to re-request it immediately. Because the requested file is usually now ready, or will be prepared within the next waiting period, you will get the new matches.