Can’t seem to view pictures

I’m using Krypton. I just add a source for my Pictures which points to my NAS. I have about 7 or 8 folders with a few hundred jps in each folder. When I go back to the main menu and select Pictures, My Photos, I can see my folders where all the photos are stored but when I click on a specific folder, the thumbnails are blank. If I click on a photo, sometimes it loads sometimes it doesn’t. I went back to the Main menu which now seems kinda stuck, I have the little circle going around and around trying to load content and my whole system is really slow. Is It trying to build thumbnails in the background? Not sure how this works in Kodi.