Drag and drop not working

I'm on KDE neon User Edition 5.18 x86_64

``flatpak override --show --user com.github.taiko2k.avvie``
```
[Context]
filesystems=host;home
```

``flatpak override --show com.github.taiko2k.avvie ``
```
[Context]
filesystems=host;
```

Start by reproducing the drag-and-drop failure on KDE neon User Edition 5.18 x86_64 and compare the per-user and system Flatpak overrides shown in the issue. Investigate how the application handles dropped files and determine whether the reported filesystem permissions explain the failure. Done means drag and drop works in the affected environment and the behavior is covered by an appropriate verification.

Written by the indexing model from the issue text.