I found that new pictures do not regularly appear in the gallery as well. I discovered with OI File manager and adb shell that they are indeed in the /mnt/sdcard/DCIM/Camera directory. I tried a few of the options here, but even re-boot, and unmount / mount sdcard didn't fix gallery. What may have worked is to open Camera Pictures in Gallery, then select Slideshow. The new pictures show up in the slideshow, and thereafter appear as icons in Gallery.
Weird, and a PITA