We're evaluating the suitability of Spine. Since Spine doesn't save I chose to look at the examples to see if they were compatible with the version of Unity we're using (updating Unity isn't a luxury we have, we're exporting to console).
I first looked at: Spine Test Drive\Assets\Spine Examples\Other Examples\dragon.scene
This example appears to be broken. None of the graphics load. I am using Unity 2019.1.7f1, I have downloaded the shaders needed to make Spine work.
I spent a few hours trying different things whilst also asking others online for advice. Others have confirmed that the dragon.scene example is broken. If I drag the skeleton asset for the dragon into the scene it works and animates when the editor is in Play mode.
This has shaken our confidence in Spine. We have recently stopped using GAF (a Flash animation conversion tool) because of discontinued support. We don't want to invest the amount of money required to use Spine when learning how to use it has been a frustrating tour of broken examples. It's like the example projects are telling us to avoid using Spine.