My only experience with honey is putting .75lb of it in a Bells Hopslam clone recipe I've made a couple times, and it fermented out just fine in my normal ale timeframe (2-3 weeks).
My understanding is that honey is a simple sugar and should ferment quickly and completely.
I don't do ciders or meads, so can't comment on that, but I did try a hard seltzer recipe once, which is just sugar, water, and yeast nutrients. It stalled about halfway through and never recovered. I believe a yeast nutrient issue of some sort was the cause, even though I followed the directions exactly... there is nothing else it could be.
With beer, you have a lot of that stuff coming from the grain. With cider/mead, I don't know. But temp or nutrients would be my first guesses.