Problems with featured picture and nextGEN gallery

Hi – we’ve come across a problem with nextGEN gallery and our theme (Bangkok Press).

Adding a Featured Image (setting: Use as thumbnail) using the normal media library works as it should.

However, selecting a Featured Image through NextGEN Gallery in the same way doesn’t – the Featured Image box shows the photo we selected, but when we update the post and look at it, the header is just default. In the editing screen it is shown, though.

Could it be a problem with our theme and if so what can we do?

Thanks in advance