I have the following weird issue, see if somebody can help. I have to computer (an iMac and a MacBookAir), both running the same version of the OS (latest at this moment). I have also Lightroom 5.5 running on both computers. I want to bring one of my catalogs from the iMac to the Air, and for that I copy the catalog files and the photos over. The weird thing is that when I try to open the recently copied catalog in the Air, Lightroom ask to convert it to Lightroom 5 first, like if it comes from an older Lightroom release. It is a Lightroom 5 catalog already! How come? If I proceed, it created a new version of the catalog (with a 5 at the end), but when it finally opens it's not really the same, missing collections for instance. Any ideas of what could be wrong? I've done exactly the same with some of my other catalogs, and everything is fine.