etcher: macOS mounted flash storage error (Won't Process ISO File)

• Etcher version: 1.5.109 (1.5.109)
• Operating system and architecture: macOS 10.12.6
• Image flashed: <none>
• Do you see any meaningful error information in the DevTools?

No matter what ISO file I present to etcher it tells me the ISO is either incomplete or corrupt. That is not the case. I have used the exact same ISO multiple times to make bootable images. So either you have a stop missing in your usage procedure or you just report that every ISO is corrupt. I have used multiple ISO files with the same result. I see no evidence that this product works at all.