It seems that layer function (search()) of GCS plugin is not called in only SnowFlat. I do not know the detailed cause. But, it seems that GCS plugin moves correctly by replacing one line of snowFlat.
qa-theme/SnowFlat/qa-theme.php (around L603) qam_search()
Anyway V1.7 is incomplete version. In particular, I think there will be many problems related to compatibility with existing plugins.