When you say Big Tiff - do you mean a large TIFF image or a Big Tiff Image - we dont support Big Tiff format only the standard Tiff Format. The Stratus software will convert a Big Tiff to a zip file of normal TIFF tiles and we can import the zip file, extract all the images and geoplace them and they will be high resolution - not sure where your Large Tiff files are coming from so hard to say.
In the Support Options command - you can manipulate how images are managed

This is likely the place where you have differences if there are any in your setup
I would have to get the image and know which versions of BC-HCE you are comparing, and what these settings are set to on both your setups to determine if this is an issue or not - if you want me to take this further please provide the data and the additional info and I will take a look at it for you
Alan