Umbraco.MediaPicker (legacy) not converted to Umbraco.MediaPicker3

[creativesuspects]

I've generated a Migration Pack in Umbraco 8.18.14 using uSync.Migrations. When running the conversion in Umbraco 10.8.6 with uSync.Migrations v4.0.0-phase.5.1 the legacy media pickers (Umbraco.MediaPicker) are not being converted to Umbraco.MediaPicker3, even though this is a default migrator that comes with the package.

Is there anything I need to do to enable this conversion?

When I copy the code for the MediaPickerMigrator from GitHub and add it to my project (as follows) the conversion does kick in, but this only works when I add the [SyncMigratorVersion(8)] attribute.

[SyncMigrator("Umbraco.MediaPicker")]
[SyncMigrator("Umbraco.MediaPicker2")]
[SyncMigrator("Umbraco.MultiMediaPicker")]
[SyncDefaultMigrator]
[SyncMigratorVersion(8)]
public class MediaPickerMigrator : SyncPropertyMigratorBase
{
    [no changes to this code]
}

By the way, the package works wonders when converting NestedContent to BlockList. 🥳