Possibly the error is the result of the 6) Integrate, composition setting. Did you leave it at “reference”?
If so, try the integration with the “full” composition mode. Don’t forget to push the apply mode button.
I should let APP use FULL composition by default when the mosaic mode is used in registration, so I’ll add this to my RFC /ToDo list.
The “reference” composition, only shows the field of view of the reference frame in the integration.
The “full” compostion shows the entire field of view, so all pixels of all registered frames are shown.
If you have a panel in the mosaic that doesn’t overlap with the reference, the reference composition could throw this error I suspect.