How to reproduce:
1. Create a new Unity project
2. Add a Canvas to the Scene
3. Create a child Inherit Canvas with Override Sorting enabled
4. Create a child Image and add a Canvas component with Override Sorting to it
5. Set the Image color to red
5. Create another child Image and add a Canvas component with Override Sorting to it
6. Set the Sorting Order to 1
7. Enter Play Mode

Expected result: You see a White Image
Actual result: You see a red Image

Reproducible with: 2018.4.34f1, 2019.4.25f1, 2020.3.6f1, 2021.1.5f1, 2021.2.0a15

Workaround: Update the red Image Override Sorting via code

Notes:
1. This only reproduces the first time this setup is created. If you close and reopen the project the Images render correctly
2. If you disable and enable the parent Canvas or change the sort order in Playmode the issue is fixed