The SVG file may be missing the height and width in the opening <svg> tag:
It reads <svg id="Layer_1" data-name="Layer 1" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 40 40">, so maybe should read <svg id="Layer_1" data-name="Layer 1" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 40 40" width="128" height="128"> or whatever you want the default size to be. Just a guess, though, as I can't get SVGs to render at all myself (which is how I found this bug report).