|My old Bernina 930e has a rudimentary kind of automatic buttonholer (a program to click through, although I have to set the buttonhole length myself), and this obedient machine generally makes beautiful buttonholes. However, it really hates making buttonholes near the edges on thick fabrics. I've discovered that the entire foot wants to be on the same level for this. So, I use a fabric shim when I run into this kind of problem. Sometimes, it's as simple as just putting a length of folded fabric under the unsupported part of the foot that has fallen "off the edge." Other times, as when I'm working near the corner of a thick lapel, I actually butt a couple of thick scraps along both edges and hand-baste them in place, so the foot is supported whichever way I turn the fabric.
That often makes the whole process more manageable.