OK, so after two attempts I finally got an understandable answer from LG . It took some time because they needed to go to the engineers.
Basically I asked if Active HDR was applied to Standard Picture Mode HDR by selecting Dynamic Contrast (to any of the ON positions) as found in the Advanced Controls as it is for say the Cinema Mode where Dynamic Contrast is found under Expert Controls. Here is the reply ;
Firstly I apologize about confusion, your query not a common one but I am pretty sure I understand what you are talking about.
If I am correct you wish to know if the Active HDR feature which tries to bring other HDR standards up to the level of Dolby Vision with some clever software tricks applies to all HDR picture modes, including Standard.
This feature should be enabled on all HDR picture modes by default if the TV supports the feature. When you have HDR content on screen the picture modes will automatically roll over to the HDR set. Each of the available modes under HDR picture mode should have this feature enabled.
The option regardless of if it’s within the expert controls section or the advanced controls does the same thing. So Dynamic Contrast in Standard Picture mode makes Dynamic metadata just as it does in Cinema mode.
To me that seems to clear the issue up and we can believe that Active HDR for Standard Picture Mode is triggered by turning Dynamic Contrast On in the Advanced Picture Settings section. Hope this clears it up for you also.