How to reproduce:
1. Open the attached project "Test Loc.zip"
2. At the menu bar click Window > Asset Management > Localization Tables
3. Select an "Edit Table Collection" tab in Localization Tables window
4. Export a '.csv' file by clicking on the three dots at the top of the Localization Tables window > Export > CSV
5. Click on the progress bar at the bottom of the Editor's window
6. Observe Background Tasks

Expected result: There aren't any not responding background tasks
Actual result: There is one not responding "Exporting" background task

Reproducible with: 2020.3.11f1, 2021.1.10f1, 2021.2.0a19
Could not test with: 2018.4.35f1, 2019.4.28f1 (progress bar doesn't exist at the bottom of the Editor's window)

Notes:
- Reproducible when importing/exporting Localization files
- Localization files are successfully imported/exported, but the progress bar doesn't disappear