I created a quick animated character, but when I export as json, and preview in SkeletonViewer, part of the character (the head) disappears. The animation looks fine in the editor, though.

I have uploaded the zipped Spine folder to Google Drive for you to inspect. What am I doing wrong?

PS I am a new user. This is the first test character in Spine. The graphics are Creative Commons, attributed to David Revoy (of Pepper and Carrot fame).

https://drive.google.com/file/d/15hYo8FWEEPm5rjRrujljIZgRIHxKeFg3/view?usp=sharing

Welcome to Spine!

To debug this, I looked in the atlas (which is a text file) and tried to find the missing image. It's there, just without the head/ part of the image name. This happens because in your texture packer settings you have Flatten paths checked:
Texture Packing - Spine User Guide: Options

This means an attachment with a name (or path) of head/Koriander-hair_back-head_main16 will get "flattened" to Koriander-hair_back-head_main16. So in the JSON data you have head/xyz but in the atlas you have only xyz so it doesn't find the region in the atlas.

Thanks so much! That resolved it. I had misunderstood the meaning of that particular option (note to self: next time RTFM!).

The next step involved testing the animation in the game engine (Visionaire) which works splendidly.

It's taken me a while to decide to purchase Spine, but it certainly is worth it now. Thanks again for the quick answer!