2021 R-Dynamic SE D200 - Subwoofer Level Control appeared and disappeared.

Hi

Yesterday whilst viewing the Audio Settings screen, I noticed that a new 'Subwoofer Level' control appeared, and assumed that the PIVI update had done this.

Confusingly, I was led to believe that the subwoofer was only present with Meridian systems. However, playing with this control certainly changed the sound of the bass. Later the same day, the control has disappeared again, leaving me with just Bass and Treble again.

I'm very confused as to whether I have a Subwoofer or not, and whether a software glitch caused the menu option to appear and disappear again.

Any ideas?

Thanks