How to reproduce:
1. Create a new project in your preferred workspace and open it
2. Connect it to Perforce
3. Create two new Materials and submit the project (This will be User 1)
4. Open the same project with a different user in a different workspace as well (This will be User 2)
5. With the User 1 checkout the Material and change its Color
6. On the User 2's project checkout the same Material and change its Metalic value to 1
7. Submit the User 2's version of the files to the depot
8. On the User 1 do "Get Latest" on the Material (The file should now be conflicted)
9. Right-click the Material -> Version Control -> Resolve Conflicts...
10. In the new Resolve Window click "merging"
11. Observe the Material

Expected result: the Material gets both the Color changes and the Metalic value changes
Actual result: the Material only kept the Incoming version changes and discarded the local one - the Color is reset and the Metalic value is changed to that of the User 2's

Reproduced in: 2020.1.0a4, 2019.3.0b3, 2019.2.6f1, 2018.4.9f1
Not reproducible in: 2017.4.32f1