OppGen Marketing Web & Digital Designer interview questions

Initially, I had a great experience. I was contacted by the company, and a phone interview was scheduled with the department lead for the Web & Digital Designer role. The phone interview went really well. The hiring manager was very engaging, and we had a great conversation. I was informed I had passed the initial phone screening, and the next step in the process would be a design assignment. I received the assignment via email, which I discovered was a landing page redesign. I thoroughly enjoyed working on the assignment, and spent quite a bit of time on it, turning it in the night before the deadline. On top of the desktop redesign, which was the original ask, I also laid out a proposed mobile version, along with a short brand guide to pull it all together. I was really proud of my work, not just because of the finished product, but because I had completed it using a program I was using for the first time. After receiving no reply, I knew something was up, and discovered my last few communications [including the project files] had gone to spam. A quick message confirmed this, and I was advised I would receive feedback within the next couple days. Unfortunately, no further communications ever came, which was very disappointing, considering the amount of time and work I spent on this project. I gave it one last follow-up and considered myself ghosted. I guess it's a lesson learned for me not to do spec work, but a response of some sort would have been nice, regardless of the hiring decision.