First, all published recipes are not reliable. Those from friends are less so.
The obvious culprit is water from the apples.
The first thing I learned to cook was pancakes, and as a kid would have other kids over for them. Why they let me and my sister access to the stove at the tender ages we were I have no idea, but we were very responsible. My sister and I were old, even as kids.
Anyway, my guess it is the liquid from the apples. Grate them thicker and squeeze the fluid out.
You are going to have to play with this a bit, at least that is my guess. But heck, it is only pancakes, not foie gras. Tossing a couple away is not a tragedy.
Just my take on things.