Will Sonnet eGFX support external Builds on Mac?

Recently trying a Sonnet eGFX Breakaway Puck Radeon RX 570 on my MacBook Pro. After going though all the Unreal Engine binaries and setting their info flags to be ‘Prefer External GPU’, I find zero acceleration in my builds on the external GPU and my MacBook cpus pegged at 100%.

If I read this correctly, the build program on the Mac is called ‘UnrealLightmass’ and is an executable. However, I don’t seem to have the ability to set this executable to ‘Prefer External GPU’.

My question is, will the Sonnet eGFX work with the Mac install of Unreal Engine?

Thank you.