Just an FYI, if your drive is Apple File System (APFS), Balena Etcher doesn’t work, nor does it surface any error to the user. I was stuck on this and just had a hunch that this could be an issue.
Opened up Disk Utility, “erase”d drive, reformatted as FAT, and now it works.
Hoping someone else that gets stuck on this finds this forum post if they’re searching around. I didn’t see any mention of this anywhere in the docs/website/anything
Cheers!