The red exclamation marks on a layer were added to indicate when there was a problem accessing one or more files on a layer. hey are normally encountered after seeing an error message, "Error occurred in opening at least one layer. LPMap::AddLayers(). Please Check file paths." when opening a saved LP360 or True View EVO project. Hovering over the layer will reveal a tooltip, which shows more detail about the missing file(s). This generally occurs when opening a saved project file where the data may have been moved, deleted, or is in a location that is no longer accessible. Project files save absolute paths to the data, not relative paths, hence, you need to repath (File -> Repath) the files in the project if you move the data.