An Album is not being displayed - why?

It is clearly in Windows Explorer (Windows 7 64 bit) but not displayed in Roon. It is
Britten: Double Concerto & Other Works with Gidon Kremer, Yuri Bashmet, Kent Nagano, Hallé Orchestra

I tried deleting it from Windows Explorer and Downloading it again from Sooloos (where it displays no problem), rebooted Roon but still no sign of it.