Well ... caught me by surprise!

[Rugby (aka Daniel or Big Dan)]

@mike

Because Roon’s importing process is based on automatic folder scanning, we need to ensure that some folders which include system files or other temporary content isn’t included. We don’t have a lot of issues with this, but the detection can sometimes go awry when bands or albums have names that match our rules. As mentioned by others, folder names that start with periods are the most common offender, such as "/...And you should know us by the trail of dead/" .

Quoted from a dev response.