Mercury Transmit changes brightness

When I activate the Mercury Transmit Preview I see a change in brightness on my secondary and tertiary monitor. One is a fully Colour calibrated Eizo.

The image is much brighter than seeing without Mercury Transmit. Just compared it to the preview on a broadcast monitor connected to a Avid Media Composer - the non Mercury brightness is correct.

It looks like Mercury Transmit is ignoring the colour management of Windows.