The only other thing I could imagine was the problem was that I was interviewed via skype and that the client had asked for my skype account (at the time there was no voice/video through upwork). However, payment was still done through Upwork which is what they care about. Not a single dispute, nothing.

I went back and forth about the money, threatening to take them to court, write blog posts etc. But, they were still sending me generic replies. At the time, I really could not have been bothered enough to hire a lawyer and go through with this. The project from which they stole my money from involved a RaspberryPi and some other sensors and modules which was at its infancy, so I have learned quite a bit, so I've let go, but a lesson learned was that I should never work through a mediator (if that's the right word), but rather directly and have a lawyer review my contract. Clients have also loved the fact they're not paying 20% extra.

It definitely has happened just read the comments, one guy with 1440$, others with smaller amounts - https://collegetimes.co/upwork-sucks/ plus other things people are annoyed by with Upwork.