I’ve been unable to upload a SVG file to Make my sign. I’m using Safari and wonder if that is a known issue or if other’s are having trouble uploading as well.
I was able to upload an example SVG file without issue using Safari on my Mac. 
Do you have any other SVG files to try to see if it is specific to your file? Are you able to successfully upload it to an online viewer like https://www.svgviewer.dev/ ?
What error are you getting on the upload @Firefli?