Hey,
I had the idea to give my main character some other costumes. The current version (working) has no skin at all just uses the default settings. So I created two new skins and added the current version of the art to skin one the new art pack to skin two. Everything worked fine in the Spine Editor. But as I exported it to Unity I ran into some problems.
The SkeletonData shows that the Atlas can't be found. I get a long list of missing regions.
And I get some error messages too:

Error reading atlas file for atlas asset: hero_Atlas
Object reference not set to an instance of an object
  at Spine.Atlas.ReadTuple (System.IO.TextReader reader, System.String[] tuple) [0x0000b] in C:\forgeAHero_repo\repo_bitbucket\ForgeAHero_current\Assets\spine-csharp\Atlas.cs:216 
  at Spine.Atlas.Load (System.IO.TextReader reader, System.String imagesDir, TextureLoader textureLoader) [0x00068] in C:\forgeAHero_repo\repo_bitbucket\ForgeAHero_current\Assets\spine-csharp\Atlas.cs:126 
  at Spine.Atlas..ctor (System.IO.TextReader reader, System.String dir, TextureLoader textureLoader) [0x00021] in C:\forgeAHero_repo\repo_bitbucket\ForgeAHero_current\Assets\spine-csharp\Atlas.cs:102 
  at Spine.Unity.AtlasAsset.GetAtlas () [0x000a6] in C:\forgeAHero_repo\repo_bitbucket\ForgeAHero_current\Assets\spine-unity\Asset Types\AtlasAsset.cs:138 
UnityEngine.Debug:LogError(Object, Object)
Spine.Unity.AtlasAsset:GetAtlas() (at Assets/spine-unity/Asset Types/AtlasAsset.cs:142)
Spine.Unity.SkeletonDataAsset:GetAtlasArray() (at Assets/spine-unity/Asset Types/SkeletonDataAsset.cs:178)
Spine.Unity.SkeletonDataAsset:GetSkeletonData(Boolean) (at Assets/spine-unity/Asset Types/SkeletonDataAsset.cs:126)
Spine.Unity.SkeletonRenderer:Initialize(Boolean) (at Assets/spine-unity/SkeletonRenderer.cs:201)
Spine.Unity.SkeletonAnimator:Initialize(Boolean) (at Assets/spine-unity/SkeletonAnimator.cs:66)
Spine.Unity.SkeletonRenderer:Awake() (at Assets/spine-unity/SkeletonRenderer.cs:153)

NullReferenceException: Object reference not set to an instance of an object
Spine.Unity.Editor.SkeletonDataAssetInspector.PopulateWarnings () (at Assets/spine-unity/Asset Types/Editor/SkeletonDataAssetInspector.cs:567)
Spine.Unity.Editor.SkeletonDataAssetInspector.InitializeEditor () (at Assets/spine-unity/Asset Types/Editor/SkeletonDataAssetInspector.cs:115)
Spine.Unity.Editor.SkeletonDataAssetInspector.OnEnable () (at Assets/spine-unity/Asset Types/Editor/SkeletonDataAssetInspector.cs:78)
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)

So I am not sure what is going on with the texture atlas. I did not change anything in my workflow while exporting, so this is a riddle to me how the skins affect this.

Using: 3.6.53 Pro and 3.6.xx runtimes

Any help is appreciated!