The svg image is disappeared when users change the content.

I have the template variable where the users can add the image. The image is successful posted however whenever the users change the content and publish the change. The svg image has gone. Please see the attach file

Does the svg display on the front end, but just not in the manager?

See post from Susan https://forums.modx.com/thread/?thread=91852&page=1

Sounds like MODx has some issues displaying a preview of svg.

Yes, and pthumb doesn't work on them on the front-end either.