Visual Studio application not showing under Windows 8.1

i created a simple one button program in Visual Studio 2017. If i start the .exe which was in \bin\debug the program runs fine (Windows 10). The program brings firefox in forground and rotates tabs in firefox. If i copy the .exe to the target machine (Windows 8.1), the program opens but showed only in taskbar. On desktop, the app is not visible. See-the-Problem

.Net Framework is installed. Maybe there is something other missing on the target machine? Thank you for help!