Hi @mauricetoet,
The error is fixed, from all available frames left, APP will automatically choose a new reference frame using the frame quality estimate after star analysis.
I have also checked if all goes well if you were to start 5) Normalize after having removed the reference after 4) Register. This is working without problems as well.
For everyone else, this error was present in version 1.036.0, next versions shouldn’t contain this error.
Mabula