Reproduction steps:
1. Open the attached project;
2. Open the scene "TestScene";
3. Enter Play mode and observe the Console window;

Actual result: an error "The referenced script on this Behaviour is missing!" shows up. The instance of ScriptableObject is not created.
Expected result: The instance of ScriptableObject should be created and an error should not show up.

Note: the bug appears when both a namespace is used and the ScriptableObject is defined as a nested class. If either of those is changed, then the bug does not appear (have look to the user notes in the Test.cs)

Reproduced with: 5.3.6p4, 5.4.4f1, 5.5.0f3, 5.6.0b6