This sounds strange. When I build it with only a SkeletonData asset assigned to the bundle, I get this manifest:
ManifestFileVersion: 0
CRC: 4012205056
Hashes:
AssetFileHash:
serializedVersion: 2
Hash: ece6130a9ffdaad2491fc32395830311
TypeTreeHash:
serializedVersion: 2
Hash: 275521779b7e09a29bd58052fa6c1799
HashAppended: 0
ClassTypes:
- Class: 21
Script: {instanceID: 0}
- Class: 28
Script: {instanceID: 0}
- Class: 48
Script: {instanceID: 0}
- Class: 49
Script: {instanceID: 0}
- Class: 91
Script: {instanceID: 0}
- Class: 114
Script: {fileID: 11500000, guid: a6b194f808b1af6499c93410e504af42, type: 3}
- Class: 114
Script: {fileID: 11500000, guid: f1b3b4b945939a54ea0b23d3396115fb, type: 3}
- Class: 115
Script: {instanceID: 0}
Assets:
- Assets/ForumTesting/Emissive/PBRRaptor/raptor-pro_SkeletonData.asset
Dependencies: []
Which version of the Spine-Unity runtime are you using?
Which Unity version are you using?