Jim, I've encountered a similar, if not identical, problem lately. I bought the X-Pro 1 and noticed, that LR4 wouldn't always open the import dialog (preferences are set to do so). Had to click "import", whereupon the SD card content was immediately shown - I didn't have to navigate to the card. Then, not all images on the card were shown and I had to remove the card and re-insert it. Frustrating! I need to add, that this was before the recent LR4.1 update (which only then offered X-Pro 1 raw support).
So, my problems took place with the X-Pro 1 only and with pre 4.1 version. I can't see, if 4.1 shows the same performance since I sold the X-Pro 1 last week. I had placed it's raw files in a separate folder for a later import when its raw files were supported, which is now the case. But I've never encountered any sort of oddities when importing files from cards used in Canon 5D or Panasonic GF1 or other raw-capable cameras.
You wouldn't happen to be using an X-Pro 1, would you?
