At Lr CC 2005.1, On Import dialog , does not appear all photos in card. approx. 100-150 images appear on import dialog, but more & more photos in card. I canceled and invoke import dialog again, it same result until Lr exit and restart.
How long did you wait? Is the card still being accessed? Are there any videos on the card, as LR will send those to another process to scan the audio of which can slow down accessing things on the card.
I ran into a similar problem using LR CC 2015.1.1; perhaps you are running into this. I had shot RAW+JPG, but the import dialog only showed the RAW versions of these, plus a couple of JPGs I had converted in-camera. The fix was to go to LR > Preferences > General, and check “Treat JPG files next to RAW files as separate”.