Since the latest update, mini-bosses spawn rates have improved dramatically. I have seen 5 mini-bosses over the last 2 days, out in the frontier. I found 3 momentus (one at FNM ) and 2 marlixes so far. So when I was building a little project in the frontier, I randomly find mini-bosses that appear. This morning I didn't realize there was a momentus behind me and he pulled me in, killing me. I think we should add the messages, you sense an eerie presence, or the ground shakes nearby, every time you log back on, when you are near the mini-boss. It would make it easier to stay alive and be alerted, instead of having a heart-attack. I don't think the ps settings affect this, cause I was on difficulty 5.
Not every time, I had one yesterday spawn without the message. I first thought that I must have missed the message while afk, but after seeing this post I guess it might be a bug.
I same here I was getting my drops after I exploded from a creeper when a momentus was guarding my stuff. It wasn't even there at first!
They still do show, but they only show on initial spawn. Not really wanting to show it for anytime one enters your view-distance otherwise it would spam you and also require tricky code to even detect that on a per person basis.