S21Ultra: I don't have an HD or VoLTE status indicator

I do have VoLTE enabled in Settings, LTE is selected  (I'm usually on band 4 or 12) but  I don't see what Samsung calls a "IMS Network Status Indicator" - I expect it is a "HD+" icon.

Also, I have never seen a wideband codec in use, just AMR NB while on calls to other mobiles that support VoLTE.

My old Mate 20 pro has always shown an HD icon.

EDIT : I ran a quick test, with VOLTE enabled, data stays on LTE, without it, it drops to 4G.  So it VoLTE works, it's just the indicator missing.