Archicad 25 not using multithread while in the "processing" phase of rendering?

[Jackson]

im unsure if this is just a quirk of archicad or an actual issue but whenever i try and photorender an image, ill see in the task manager that it only uses a single performance core (first image) during the "processing" phase of rendering.

once it completes its processing it only then will start to utiliise the whole processor (second image) 

is there some setting i need to change so that the processing phase actually utilises the multicore functionality or is that just not something that is supported in archicad yet?