This might still be a known issue they’re actively trying to fix. They said it was fixed in an upcoming build, but it still seems to have some bugs.
The current work around is to use an array rather than a single property reference to your custom device. Or use tags as a way to get references to your other custom devices. Then direct public method calls between them should work while maintaining instance property values.
Ideally I would like to see them add Verse support for public event listenables, then we wouldn’t need to make direct calls between custom devices.