Deleted assets not being removed from asset index

[ademers]

Description

Assets deleted via file system/(S)FTP are not removed from the Asset Index.

Steps to reproduce

1. Create an asset volume.
2. Add assets to this volume via file system or (S)FTP.
3. Update Asset Index.
4. View assets in CP via Assets tab. They display as expected.
5. Delete assets in volume via file system or (S)FTP.
6. Update Asset Index, and do not see message that deleted assets have been removed from index.
7. Assets are still visible in CP Assets tab.

Example scenario

Upload 4 files to volume via FTP. Update assets index and assets appear in CP as expected. Delete the same 4 files via FTP. Update assets index, but deletion is not recognized, so deleted assets are not removed from index and still appear in CP. Upload a 5th asset file via CP or FTP, then index. Deleted files are removed from index and 5th file is added to index as expected.

Additional info

• Craft version: Pro 3.0.9
• PHP version: 7.0.29
• Database driver & version: MySQL 5.5.5
• Plugins & versions: https://cl.ly/2s1q08421q3w