exFat Hard Drive not showing up on mac OS X 10.7.5
I haven't tried this myself as I haven't had this similar problem, but I read that it is the cluster size that you select during formatting which is the issue. If you plan to use with Mac, format the drive using a cluster size not more than 1024. 
The problems I have are kind of different with exFat and mostly when the drive is not ejected properly under mac, everytime this happens i have to do a verify/recover step which takes quite a lot of time as mine is also a 1TB drive.