Icon Color and Version Selection Problem

Launcher can not recognize all my Unreal projects. (Maybe some bug(?) of the Launcher ver. 7.5.0). Howecer, to open my project in its folder, there I found that the color of the Unreal project Icon is black as shown in the attached file. In normal case, it was blue. Now, I cannot select the Engine versions by right-clicking on the Icon. Does this black color show an evidence of expected problems? I have installed Windows 10 and Visual studio community 2017 and ue4 version is 4.19. Please give me ideas to solve the problem.