Is it common to be Initiating 99% of interactions in hostels?

I've traveled a fair bit and almost always chose to stay in hostels for the obvious reasons. I've come a long way to overcome my shyness and introversion and honestly have no issue going up to people, saying hi and introducing myself and it almost always goes well. However, I could literally sit down in the middle of a dinner or social activity etc and be completely ignored and overlooked unless I strike up a conversation first.

As I said, I don't mind doing this, but at this point I'm starting to become self conscious and think I might be off putting somehow. Your first instinct might be to say it's my body language or something, but I find people who are sitting alone to pretty much always seem to have uninviting body language, yet I still take the initiative to go up and say hi, which they are always receptive to. For myself however, I always try to look relaxed and open. Why is it that literally no one does the same for me?

Is this a common experience for everyone else as well? This is only something that I've noticed recently and it's starting to weigh on me.