why are some of my photos only showing up as a grey box with the file number at the bottom. When I click on them some of them show up and some do not?
How are you exporting? Have you confirmed that the Image Export Preset parameters are what you want?
If doing a File>>Export>>Version… of a right–click Export>>Version…, you will get a dialog lookinng like this
I image your Export Preset to set to something besides orginal size. Make sure that is set to orginal size.
Retrieving data ...