Hi, I quickly tried on a fresh installation. It should work. Can you check if the FTP directory /wp-content/uploads/jvm-rich-text-icons/ gets created? If not I suspect some issue with the uploads folder and the CHMOD settings. Are you able to upload normal files to the media library in this webiste?
Another issue might be a strange (or to long) file name. Please try something simple like: icon.svg
I can’t solve this issue without any extra information. Maybe check the error logs for any additional information on this issue. If you have m,ore info getr back to me.
Kind regards, Joris