What version of the Mac OS?
What version of Lightroom (x.y.z)?
What are your Export dialog settings?
What viewer are you using to see the exported JPG files?
So what file type are you exporting? jpg, tif, original?
Only the jpg and tif will export with your edits showing in the exported file!
('Original' means SOOC- Straight out of camera.)
A screen-clip of your Export dialog may help others answer the question.