How to reproduce:
1. Create a new Unity project
2. Import the attached "test.fbx" model
3. Open the Inspector Window of the imported "test" model
4. Click the "Extract Textures..." button in the 'Materials' section
5. Open the Inspector Window of the "StingrayPBS1" material of the "test" object

Expected results: The Occlusion map is attached
Actual results: The Occlusion map is missing, "Unsupported DDS file" error is thrown in the console

Reproducible with: 2019.3.0a8, 2019.3.0b11, 2020.1.0a13
Not reproducible with: 2017.4.35f1, 2018.4.13f1, 2019.2.13f1

On Unity 2019.3.0a1 to 2019.3.0a7 an fbx import was stuck in an infinite loop

Additional note: The model was created using Maya with StingrayPBS shader, and then exported as fbx