Control Room question

I had Control Room mastered with my last interface - Presonus RM16. This device has a main out and also 8 configurable outputs. Method:

  1. Disconnect Main Out and connect speakers to outputs 7&8
  2. Add 3 Cue sends - 1/2; 3/4;5/6; add Speaker send to outputs 7&8.
  3. Send to Cue sends from Cubase mixer, turn up these sends in the Presonus app (where these 8 outputs appear as subs)
  4. Stereo mix enabled by turning up the gain on sub 7&8 in the Presonus app.

New interface: Presonus Studio 192 + DP-88. Follow exactly the same procedure. However, unless I activate the Stereo Out in F4 - to “Main Out” I don’t hear a mix. No level at all sent to 7&8 from the Control Room. Is there any way the settings are corrupted from my old prefs? Is this an issue? What have I missed? Thanks very much.