Mine always dissolved. FWIW Servomyces is a huge waste of money. It is a way for you to use yeast nutrients while still sticking to the Reinheitsghebot. Basically it is yeast infused with zinc. I personally rarely use any nutrient except for my starters but when I do I use the Wyeast nutrient - it has zinc and yeast hulls, etc. but is only a fraction of the cost of servo.
I have also been using the Wyeast nutrient, along with some yeast hulls (available from wine making suppliers), because the Wyeast has the zinc and other nutrients as well. My thinking is that the combo of hulls and nutrient gives the best of both worlds.
But, Majorvices, you say that the Wyeast has yeast hulls in it? ( I suspected so from the way it looks) Their website does not list that, at least as far as I have found. Or most of what else goes into it, other than zinc and a couple of other things. Is that info posted somewhere?