Ihsahn, alongside his musical colleagues in Leprous, Emperor, and Starofash, took part in the Mnemosyne Productions' Motstrøms live event in September 2018. You can now check out the group doing Ihsahn's own song "Until I Too Dissolve", which if anything is worth a watch because that opening riff is just so deliciously classic heavy metal.
Audio from the event has since been mixed and mastered, so assume there's a release coming sooner or later.