I have a strange issue. My files import and open fine on my iMAC Lightroom 4.4 but won't import the files on my macbook Lightroom? Any ideas?
D750 files cannot be opened in Lightroom 4.4. You need at least Lightroom 5.7 to open these RAW files.
If they are opening fine on one computer, then it does not have Lightroom 4.4, it has some later version.
Get the free Adobe DNG converter, try again. But I agree that if one machine can import them, the other should too.