ABBA, the legendary Swedish pop group, has been inactive as a recording and touring entity since the late 1980s. Although there was a one-off live performance for a private event in Stockholm in 2016, there have been no official statements or actions from the band members indicating a commitment to a proper musical reunion or the creation of a new album.
The origin of the rumor about an "Opus Ten" album is unclear. It's possible that fans' enthusiasm and desire for more ABBA music have led to speculation and rumors, but these remain unverified and unsupported by any official sources.
Until ABBA or their official representatives make a formal announcement, any information regarding new albums, reunions, or studio recordings should be considered purely speculative.