Missing thumbnails at startup when group by folder is enabled
Description
When using with group by folder in video panel, thumbnails are not displayed at startup. Instead, it is just the default icon.
Thumbnails appears when rotating the device though.
This does not happen with group by name.
Context
App version
3.3.0-dev, revision 13bf387f
Android version / Device model
Android 7 on Shield Tablet K1
Android 9 on Sony Xperia XZ2