Sprite Asset changes are unsaved after updating sprite atlas

How to reproduce:
1. Download and open the attached "repro_project" project
2. In the Project window, select Assets > Resources > Sprite Assets > Button
3. In the Inspector window, expand the Sprite Character Table
4. Observe the first sprite displaying two vertical lines
5. Press "Update Sprite Asset"
6. Observe the first sprite displaying a medal
7. Close and re-open the project
8. Repeat steps 2-4

Expected outcome: The first sprite displays a medal
Actual outcome: The first sprite displays two vertical lines

Reproducible with: 2021.3.17f1, 2022.2.13f1, 2022.3.0f1
Could not test with: 2023.1, 2023.2 (Project breaks/console errors when upgrading)