How to reproduce:
1. Open user-submitted project (NestedPrefabBug)
2. Open the scene 'SampleScene'
3. Select the 'Canvas' GameObject and attempt to override changes to (Mesh Filter) and Text Mesh Pro (Script) components

Expected result: changes in the components are applied in the prefab and the 'Overrides' drop-down indicates that there are no overrides
Actual result: the (Mesh Filter) and Text Mesh Pro (Script) components remain in the 'Overrides' drop-down menu even after changes are applied

Reproducible with: 2018.3.0b9, 2019.1.0a8

Notes:
Note that there is no (Mesh Filter) component on the 'Text' GameObject upon first opening the project, it only appears after overriding the Canvas prefab
The (Mesh Filter) component always reverts to an empty string upon overriding the changes