Hello,
If you have uplodaed the SVG icons, 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 (set your values) to your <svg>
tag like it is shown: http://prntscr.com/m4n0qw
Then you will need to re-upload your icons in WordPress Dashboard.
If it does not help, deactivate all the plugins not related to the theme and switch the parent theme, check the issue, if the problem remains, leave the plugins not activated and provide the site admin access to the private area.
Best Regards