Nested Senior Software Engineer interview questions

Full day series of interviews, including two rounds of pairing. You get to meet a range of people within the organisation, including C-level people. They pay you for the day, so you're not left out of pocket. The process is pretty decent, and by the end you think you know them and they know you. The interview day went well, and they informed me I'd impressed in almost all aspects, yet decided not to offer based on 'feeling I wasn't the right fit'. No examples given. I pressed them for a more satisfactory explanation and was promised one, but when we spoke again there was still none given. When I continued to ask for some, any sort of example of how I might not 'fit', they mumbled something about "your questions about diversity". It appears that they did not like me enquiring as to their diversity policies! Which I felt fair to ask, as their staff are overwhelmingly white and male. They've taken down their full team page, possibly because the lack of diversity in it was a bit embarrassing. The biggest tell for me is that their behaviours directly contradicted their value of "open, honest communications". I wonder whether a company that cannot hold to their stated values can be trusted.

Simple initial phone screen - basic questions, what are you looking for etc... Technical phone screen - call with an engineer, basic tech questions, system design On-site (full day) - interesting day, mostly a bunch of chats with a few engineers, CTO, and a product manager. 2 session of pair programming. Based on the feedback received they really judge even if you are not used to pair programming. Suggestion to work on this before hand. Interviews were structured but seemed to be not be a 100% thorough in terms of technology, system setup, and environment for developers. (Maybe suggest for candidate to bring their own) Interview was easy but I felt it didn’t judge my technical skills too much, but rather my ability in specific areas that they expected but did not mention or preferred style wise. (Expected TDD for development practice but didn’t not mention this until feedback)