Questions posées lors d’un entretien d’embauche pour Machine Learning Engineer chez ONYX InSight

I applied around January 25th, 2019 via LinkedIn. Then on February 20th the recruiter reached out via e-mail where he sent me a "knowledge quiz" consisting of 3 parts: 1. a general machine learning part with 6 questions, 2. a predictive maintenance section requiring some in-depth knowledge in mechanical engineering (the posting said nothing about needing to have pre-requisite knowledge in this area) with 7 questions and 3. a machine learning task which I needed to develop. I was given 3 days to complete the "knowledge quiz" (2 of those days were weekdays). Item 1 was straightforward, but items 2 and 3 were far more involved. I had to do quite a bit of research to arrive at answers for item 2. Item 3 was a challenging, long but fun exercise. Completing all 3 items in time was a challenge given the fact that I have a full-time job. After handing in the "knowledge quiz", the recruiter contacted me back on March 6th stating that they were "impressed" with my results and invited me for a Skype interview on March 12th. They then rescheduled the interview twice and they ended up wanting an in-person interview on March 14th. The in-person interview was a 2.5 hour long affair where the interviewers arrived late to the conference room booked for the interview. They also seemed somewhat unprepared. For example, it was supposed to be a conference call with people from all around the world, but the laptop they were connecting through ran out of battery, and had to rush to get a cable for it and connect it back. One of the interviewers kept asking me questions specifically around my PhD (which had nothing to do with the role) in a somewhat rude and grilling manner (he had to leave mid-interview to complete other tasks he had to do). The recruiter was present in the interview but did not participate at all. The bulk of technical questions relevant to the position were made by another remote employee, who asked me scattered questions about my exercise and about general machine learning concepts. If I understood correctly, I did well on this interview, but their main concern was my level of experience for the role, and so asked me in an ambiguous way if I could follow up on my already long machine learning exercise (i.e. try other models and compare with my initial solution), to which I said I could follow up if asked. I then asked questions I had about the company which they answered in a satisfactory way. All of the interviewers except one then started disconnecting/leaving. The remaining interviewer and myself pleasantly chatted for a bit and he told me that he thought that I "would be a very good fit for the role" and showed me around the office, introducing me to several employees and having chats with each. I wrote them an e-mail asking when they wanted me to hand in the follow-up exercise. The aforementioned remote employee answered "How long you think it will take to build a reasonably accurate model?", so I told him I would work on that model over the weekend (it was Thursday night) and hand it in on Monday the 18th of March, as I would be very busy the following week to be able to work on anything other than my job. I then managed to have a functional model ready on Monday the 18th of March and sent it to them with annotations of things to improve and a discussion. On the early morning of Monday the 25th of March I finally got an answer saying that they would be moving forward with another candidate. Because of the level of effort and flexibility I put into this interview, I respectfully replied to get feedback as to what I could have done better. It is still soon after the fact, but I have not yet received a response.