The SVG file does not display after uploading it to the server.
VM 4.2.18.11050
Since it doesn't create a thumbnail from a SVG, you will have to copy the URL from the main image into the thumbnail field.
I think an improvement could be, when it auto detects the fact it's a SVG and it will copy the URL to that field by itself, instead of having to do this manually.
I understand it perfectly, but it is a bug, because in vector files the concept of a thumbnail does not exist at all - there is no need for it. So let virtuemart just display the original file - it's probably not hard to fix