Hi Biplab; I am using 11.5.1, OS10.4.3. Please keep in mind that this problem is not a limitation issue. It is not that I am creating an image that is too large. It is not that I placed an image too far from the origin.
I have created images and viewports that initially work. Everything looks and behaves fine. But at some point, when I go to a saved view that has viewports, the viewports are gone.
The image is a house that is 18 feet wide by 80 feet long by 30 feet high, drawn at 1/4" scale. The viewport is set to 1/4" scale. The program by itself changed the viewport to millions of feet wide.
This behaviour is more in line with corruption than with the idea of software limitations. This is sporatic and unpredictable behaviour.
By the way, I have sent the offending file to Yi at NNA. I hope that you will pursue this investigation and find a solution. Thank you for your help.