Material missing when load UI prefab from assetbundle with a custom font as dependency in 5.3.5p3

repro step:

1.Open My project with unity5.3.5p3, load Scenes/Main.unity.
2.Run game in editor.
3.'Canvas' has a component 'TestPanel' will load three UI Prefab by three ways.
4.Load UI prefab from assetbundle with a custom font 'greennum' as the dependency.When instantiate the prefab, the font material is missing.
5.Load UI prefab from AssetDataBase, the 'greennum' 's material is perfect.
6.Load UI prefab from assetbundle, and then manually load 'greennum' asset, then set the Text.font to...

Material missing when load UI prefab from assetbundle with a custom font as dependency in 5.3.5p3