Code doesn't work in desktop IDE, works in online editor

Whenever I upload code through the installed legacy IDE, it says uploaded successfully but then the code just doesn't appear to run. I've tried multiple sketches, such as the default blink. Code does however run if i upload it from another computer or from the online editor. I've checked it's the right port, reinstalled the IDE, tried both legacy and the newest version. What could be the problem? Thanks