The image size is invalid. raw image size must be aligned to 512 bytes, this is why
we block such images in the UI.
Is it possible that the image was truncated?
According to qemu-img info, the size is 17179869696. qemu-img lie about the size by rounding
up to the next multiple of 512.
I think this will fix your image:
truncate -s 17179869696 LoadMaster-VLM-184.108.40.206.17004.RELEASE-Linux-KVM-XEN.disk
After that uploading the image should work.
Downloading the image again and verifying the image checksum with the vendor is probably
a good idea if you are not sure about the contents of this image.