ThousandEyes interview questions

The company's CTO contacted me via LinkedIn and offered to start an interviewing process. After my agreement I was redirected to an HR person and we scheduled a phone interview with the CTO. He called on-time and we talked for about 45 minutes. It was a pretty nice and smooth chat after which he suggested to continue to the UX challenge. In the UX challenge one should download their free trial, analyze it and suggest a redesign to a page, an interaction or a workflow. This part is pretty tricky since it's a very open challenge and they do not tell you what exactly to do. It's also a little annoying that they give you a challenge based on their product (free labor). They request to invest 4-6 hours and give you one week to work on it. I submitted the work two days before the deadline and invested more time than was requested: prepared a heuristic evaluation, which discovered usability and other bugs in the system. In addition I submitted a high fidelity interactive prototype of a chosen workflow (high fidelity was a requirement). They sent me a feedback email and left me a voice message, gave a positive feedback about my analysis but a very general and vague feedback about my design "your design is not intuitive/consistent". They didn't give an opportunity to explain my design via phone. I would say that throughout the process they were responsive, polite and nice. However, one should be aware that the evaluation of his/her design challenge will be (probably) done by a product team in which there is only one junior UX Designer and the rest have engineering or business education.