Front camera not working on OnePlus 5T

Since yesterday my phone's front camera hasn't been working. - Not working on most apps, including native camera. While touching "switch camera" button in camera application, nothing happens. - Instagram images from the front camera displays a distorted, stretched image of the rear camera. - In Dialer keycode(secret code) *#808* for Oneplus devices, "front camera preview" displays rear camera's image. But "camera test" makes the app close(force close) without any error info. - If I'm not mistaken, during a video call on WhatsApp, the camera froze along with the app, which became unusable until I restarted phone. After that the camera hasn't worked ever since. What I've tried so far: - factory reset - safe mode - several camera apps - going back to stable (I was using beta) Nothing worked. Any suggestions?