Help Needed FT 817 and FLGIGI

I am running LinuxMint to a FT817 via a ZLP Digimaster ProPlus. Using supplied USB lead from ZLP to computer; CAT lead to the 817; and audio in/out from 817 to computer mic/speaker sockets. Having great difficulty in getting FT8 or FLDIGI to operate. After some weeks now have FT8 receiving; but no rig control whatsoever! FLDIGI is even worse!!!
Linux is OK for Drivers and finds the audio in/out ok.

Everything works OK if I revert to Windows, but I would prefer to leave Windows for good.

Clearly I have missed something, or am approaching from the wrong direction, or using the wrong rig-control set-up.
Any advice/ ideas would be most welcome
Mike G4TWW