This has happened twice. Two different SDCards.
I shut down my camera.
I remove the SDCard
I place the SDCard into the SDCard slot on my macbook.
Random files which I could view on the back of the camera are now corrupt. Even I place the SDCard back in the camera they are no longer viewable.
The first time I lost some meaningless photos. This time I lost some important ones. Ihave copied the damaged files to a cloud drive in case there is hop of rescuing them.
I am running the latest firmware on the camera and the latest mac updates.