Hi Rinze, 

To the best of my knowledge, we have not received other reports of this behavior. That doesn't mean that other users aren't experiencing it, though. If you can provide us some more information about the types of optimizations that you're running, we can definitely look into this. 

It would be great if you can send us the following information:
 

• Archive file of your system or a simplified system which demonstrates the same behavior. 
• An overview of what you're analyzing during your optimization. 
• An description (or copy) of one of your Python scripts. 
• What release of OpticStudio were you running before installing OpticStudio 20.1? 

I understand that such information is not always shareable, especially publicly on a forum, so you can also take the discussion offline while we troubleshoot. If you'd like to do that, feel free to open a support case here on MyZemax or send us an email with the details. 

Thanks,
Nick