I have browsed the troubleshooting part of the docs and could not find a reference.
Then I saw one thread here about breathing blue but I have not got any actual problems with my Core.
Another thread about the different colour codes does not list “breathing blue”.
So, what exactly does it mean?
My Core works fine, but once in a while my breathing cyan turns into breathing blue for a while and then comes back to breathing cyan.
Sometimes the Core does still respond to cloud commands, other times there is a noticable delay.