This is an odd one but maybe someone else has come across it and it could well be a problem with Lightroom and not C1. I'm not sure. Anyway I have a folder on my Mac where I store all my Raw files. When I was using Lightroom only, before I started using C1 recently, I had always imported into Lightroom from the SD card and created a sub folder in my Raw file folder where the files are copied to. Yesterday I came home from shooting and decided to use C1 to import the Raw files and at the same time keeping to the same folder creation strategy I use in Lightroom. This worked fine. My plan then was to go into Lightroom (I still use Lightroom) and import the same Raw files from the same folder into the Lightroom catalog. After doing this I went back to C1 and noticed that this folder was now showing as Offline. So the import into Lightroom had done something. On closer inspection I noticed that Lightroom had changed the file names, adding -2 onto the end of every file name. C1 obviously couldn't find the files, hence the offline status. I renamed the files back to their original names, removing -2, and C1 was fine again and the folder was no longer showing Offline. But now Lightroom obviously couldn't see the files!
I'm sure there is some setting somewhere that I'm missing. Surely it's possible to use Lightroom and C1 alongside each other in this way?