Surround routing question

My engineer is mixing in 5.1 and he’s sending me 6 mono files back on each cue to check mix and 5.1 balance check. I have L, R, Ls, Rs all playing beautifully. But his center and LFe (tracks – signal is hot enough and shown) are not being SENT to the Master out - and thus not playing back with the other four (even though I routed them there).

For ALL of the new audio channels I set up - When I set up a NEW 5.1 audio channel and THEN ‘route’ to one of the 5.1 speakers – an error message says

“Sorry, this input configuration is unknown or not supported” (I hit ‘ok’ anyways and the four mains work just fine BUT not center and Lfe).

In my sequence just playing back I can ROUTE signal to any of the six speakers so I know the card and all cables are fine.

(I have RME multiface card btw).

Thanks for any help or advice.