FITS File Issue with PixInsight:
I discovered the reason why the FITS files could not be opened in PixInsight. Upon investigation on my Observatory Mini PC (running PixInsight version 1.8.9-3), the software was unable to open the FITS files for some unknown reason. However, when I copied the files to another computer outside the observatory, PixInsight worked perfectly with the 533MC camera FITS files.
While the issue with the Mini PC remains unresolved, I am confident that this is a localized software problem and unrelated to the camera itself. For now, this matter is considered resolved.