Hello. I have started using Tropy recently, and I have noticed that several of my photographs are not visible. I can look at the photograph as an icon, but when I click on it, there is a blank screen. Also, there is a small error sign to the right of the photograph title. Finally, when I try to click, "Show Photo in Folder," nothing appears. Thanks for the help! I am using a Mac OS Mojave 10.14.2.