Thanks for the update!
I see from the ADV7623 scripts (ADV7623-Ver1-12Cust.txt), there is an ADI recommended write to IO map 0x1F:
B2 1F 20 ; ADI Recommended Write
I don't see any scripts that set this register to 0x30, so I think only 0x20 is supported.
I hope this helps!
-Matt