I feel your pain.
Yes, I have had similar experiences, and they have shaped how I present findings, and perhaps sadly, my loyalty as an employee in general.
Because while there is a certain degree of “I could have done this differently, or argued this more persuasively, or found allies to help promote this way of thinking, or delivered that presentation differently”, I’ve also learned after having worked in a couple of organisations that were large, and suffered from extraordinary political tensions between departments and individuals, that sometimes it’s simply not possible, as one person, to effect the change that is necessary. I had the realisation after one contract where 18 months of work was shelved because someone upstairs had a change of heart, that I am not an organisational change consultant with the authority to restructure a corporation or remove incompetent managers from positions where they wield the power to complete screw up everything.
When you’re faced with a situation that is that frustrating, you can choose to fight, fold, or walk away. It took me swallowing some professional pride to walk away from that one project, but on the flipside, becoming a freelance consultant was one of the best decisions I’ve made, and it freed me up to embrace a whole range of opportunities that I wouldn’t have been able to if I’d stayed in that role—opportunities to work with amazing new clients, as well as do things like team up with Luke to start this website, for instance.
Hope that helps. Good luck!