When putting a C compiled pdx in the PlaydateSDK/Disk/Games folder, the launch icon will show up but the pdx will not actually launch. Launching Lua projects from the Disk/Games folder seems to work fine. I have tested in both Windows SDK 1.9.0 and 1.9.1. Here is a video of what happens when trying to launch the C Hello World example:
Thanks for the report, we'll take a look. In the meantime, you can run games from any location on disk by using the File Open menu or drag and dropping the game on the Simulator.