I had the same problem. I was able to fix it by uninstalling the VS package. After that, I downloaded the VS package from the Qnap-homepage and installed it manually. (QVS_4.1.0.327_20251002_amd64.zip) After the manual installation, everything worked and the console was visible. Maybe this helps someone and works for you as well.
System: QTS-264 FW: QTS 5.2.7.3297 / VS; 4.1.0.327