Ever had a project that kept being met with one barrier or delay after another? And when it was time to present it, one of your colleagues did so and took full credit for the entire endeavor when they were actually just passing by to get another cup of coffee while you were putting in the research and fine tuning things. (Blood boiling yet?) Or you discover that your boss has reassigned the project to another person without informing you of the change. (So that's why people keep ignoring your requests!) To add insult to injury, full credit for the effort is being given to the other person, who has morphed it into something less than what was in the works. But when things fall apart or a flaw in the execution appears, you are the one put into center stage to handle the fallout. (Thank you, Management.)
We're told how to handle the situation when the colleague takes the idea and presents it as their own. Is it plagiarism or just plain ole theft?
Then there's the matter of the reassignment without notification. What is that telling you about your manager? Maybe they have little confidence in your abilities. Perhaps you have a history of cost overruns that need to be avoided. Oh dear, maybe it's because few, if any, of your colleagues are willing to work with you because of your style or poor communication abilities - the ideas are in your head but they tend to stay there or only seep out in droplets, leaving everyone else in a fog. So you ask the boss what happened and they admit, "Oh, I like John/Jane Doe. They're nice and I enjoy working with them so I put them in charge. Besides that, they have done projects that have been very popular in the past. It just made sense to do it the same way with Mr/s. Doe."
Credit for the work, track record creating future opportunities, those are history unless there was some type of record being kept of what you initially started (your proposal, the initial work product), publicity, requests and approvals). Make certain those are in place as well as documented in your portfolio or resume as accomplishments.