Frame Offset for Histogram/Vectorgram in VSE

Apologies if this is in the wrong forum section, I couldn’t find one specifically related to VSE.
I’m trying to colour match two different video clips within Blender VSE.
I’ve opened up two preview windows and have applied a frame offset to one of them to be able to look at two different clips at the same time.
I have tried to do the same thing for a pair of vectorscope windows, so that I can more accurately compare the colour, but they both seem to display the information for the current frame and not the offset frame, despite setting up the frame offset correctly.
Is there any way to correct this, or should I make a bug report/feature request?