I'm experiencing this issue since a month or so. I was using the camera and I received a message of some memory error, but was able to continue taking pictures. Then I realized that the pictures were not showing up in the gallery.
I connected the device to my PC and the files are actually there. In addition, I am able to continue taking pictures and access the files when using the camera (I touch the recent photos icon and I can see them).
I have tried many things, such as removing the DCIM folder, erasing the .nomedia files, erasing data from the internal memory, and none of them seemed to work. Could anyone help me?