Reproduction steps:
1. Open the project "GameBase-client.zip"
2. Open SpreadSheet Scene
2. Click on the "TestObject" in the Hierarchy
3. Find a Texture 2D like "ImageSplash" in the Project
4. Drag the Texture to the Inspector -> Test (Script) -> Images (label)

Expected result: A Sprite gets added to the Sprite array in the Serialized field in the Inspector
Actual result: Empty element gets added to the Sprite array in the Serialized field in the Inspector

Reproducible with: 2020.2.0a13, 2020.2.3f1, 2021.1.0b5, 2021.2.0a3
Not reproducible with: 2019.4.19f1, 2020.2.0a12
Can't test with: 2018.4.31f1 (this feature not implemented)

Notes:
- Code to reveal the Sprite array in the Inspector: public Sprite[] images;
- if you add [SerializeField] tag, the issue reproduces
- if you add [NonReorderable] tag, the issue does not reproduce