I don't know of any bug in glide slope, AFAIK all works perfectly, see the previous post, the glide slope capture mode activates when close to the glide slope. Before the GS is captured, the horizontal bar of the FD continues in ALT mode if it was previously activated (I recommend to do it that way, and of course, intercept the glide slope from below the glide). If you still see some issue please provide detailed info. Though I'm pretty much sure there's none with glide slope.