My first time out in mine was the Yorkshire 3 peaks, not the best idea but they were fine. I was on another walk, low level, and climbed over a style when the boot began to press into the ankle. As you say there was no ridges or hard points, the boot has good ankle padding. I tried various lacing patterns with limited success, and foam padding. I have a pair of trail shoes, Oboz, which occasionally does the same on the ankle! Only thing I can think of is I sustained some kind of injury, exacerbated by the boot. Fortunately the issue has resolved with the boot but still continues with the shoe!