Missing HBCC Memory Segment Button?

I have a Gigabyte RX Vega 64 Air (black plastic not 'silver'). I want to check out effect of various HBCC settings.

 

In Radeon Settings > Gaming > Global Settings there is no "HBCC Memory Segment" button. Thus I cannot play with HBCC.

 

I get this in Radeon Software Version 17.8.1 and 17.8.2 and 17.9.1.

 

Why might this be the case?

 

Do I need to buy an Vega FE card to have access to HBCC controls?

 

Any help much appreciated, and thanks in advance!

 

Here's the system description in the attached screenshots:

Also: R7 1700, Asus Crosshair Hero VI.