Well I finally got out and about with my XT2 and battery grip (see previous post above). The problem is still there. Whilst my camera is being carried it is switched off. When I switch it on sometimes the icons for the grip battery show red, i.e. low charge. If I then switch it off, take out the battery tray and put it back in then it works fine. So after being without the grip for two months the camera for one month of its guarantee period with no result I have come to the conclusion that it is a design flaw.
The problem occurs when I use my 100-400 lens (and 1.4 converter) carried using my Black Rapid sling strap over my shoulder. It may be said that I should not carry it this way. Perhaps not but if Fuji want to compete with Canon and Nikon then they have to make their equipment competitive. This is how i used to carry my Canon 7D MkII with Canon 100-400 lens with no problem at all.