I have uploaded an SVG icon and it looks good. http://prntscr.com/nshy6p
The reason is your SVG icon.
You need to open your SVG icons file with some editor like Sublime Text or default system text editor and add width=”31″ height=”40″ attributes to your <svg> tag like it is shown: http://prntscr.com/m4n0qw
Then you will need to re-upload your icons in WordPress Dashboard.
The reason was svg settings. SVG settings must be: (adobe illustrator settings for svg)
Type: Convert to outline
Image location: Embed
Encoding: ISO 8859-1
Any other setting must broke svg file and theme layout