On my 1810c, the headphones remained active, while the mains were muted.
Intel i9, 32 GB RAM, 7 TB SSD Win 11 Pro PreSonus Studio 1810c Studio One 6 Pro MuseScore 4 Melodyne 5 Studio Acoustica Pro 7 Guitar Pro 8 Gig Performer 4 NI S61 MK3 Focal Shape 65 Beyerdynamic DT 880 Pro, DT 770 Pro