I am in the process of Adding a large (6500 images and 15 videos) to a new catalog. First time running Lightroom 6. When I click on the "Add" button, I don't get any indication that it is doing anything. I've clicked it several times. I would expect some form of progress bar or greying out the Add button. What's going on? Is it actually adding my images? Seems like a weird user experience if you ask me.
The Add entry at the top of the Import dialog it to tell LR to leave the image where they are and ADD them to the catalog. Then you Select the images, Folder, you want to Add to the catalog then click the Import button at the bottom right of that dialog window.