Playing DTS HD MA tracks with matrix modes on Denon AVRs

When playing a 5.1 HD audio track on my 7.1 system, my Denon AVR 988's on screen display shows the matrix mode used with 5.1 Dolby TrueHD (except "NON MTRX" mode) but it does not show any matrix mode used with DTS HD MA or HR, even though MTRX ON, PLIIx CINEMA, PLIIx MUSIC and ES MTRX and NON MTRX are selectable options under Menu/Parameter/Surround Parameter and when any of them is selected the effect of the respective matrix mode is discernible.

E.g.: When I play a 5.1 Dolby TrueHD track with the matrix mode of "PLIIx MUSIC", "Dolby HD + PLIIx M" lights up on the on screen display of the AVR. When I play a 5.1 DTS HD MA or HR track with the same matrix mode, "DTS HD MA" or "DTS HD HR" lights up on the on screen display, as if no matrix mode has been selected.

What is the reason for the difference?

I thought this would be the case in most if not all Denon AVRs. If not, I will ask this question in the Official Owner's thread of my AVR.

I will appreciate your comments and/or direction in this regard.