I'm in a similar boat. I feel your pain.
I was an engineer and very early employee at a startup. I helped grow it from four clients to many millions in revenue and a successful exit. I nurtured a team of amazing engineers. I felt like I needed to stick around to see the product off to a good start and my team thriving at their new home. I was also excited because I hadn't worked at a large company since I was just out of college and I was interested in the unknown challenges that awaited.
Our parent company isn't quite as bureaucratic as yours sounds, but it's more bureaucratic than our original company, for sure. But they said all of the right things. More resources. More opportunities for personal and team growth. But things wouldn't change and we'd be left alone to continue our success but with more fuel and maybe a slight shift to integrating more smoothly with the rest of the company's products.
I also found myself in a leadership position, so I thought I could change what few small things I noticed as a bit inefficient in the the culture to be a bit more responsive.
Long story short: I'm looking for another growth stage startup to join. I probably should have done so right away.
First warning -- the new company was obsessed with what title I should have. The startup didn't put much weight in titles. We did what needed to be done. My official title was Director of Engineering -- mostly to make clients happy when I talked to them, but they definitely could not have that...that tier was full. I ended up a Solutions Architect and Technical Manager. Ok, cool. Similar responsibilities and team.
Second warning -- lots of leadership changes at the home office. We've had three CEOs since we've been acquired. We're just the right size to be a stepping stone for ambitious leaders. It's kind of amazing that we have CEOs step into a very complex organization selling very complex solutions and they expect to learn enough to make an impact in a month. Then they start to pursue their agenda with verve! So...they inherit the broad brushstrokes of the previous administration, add a few of their own, and the organization is off on a new adventure. Unfortunately, it's a recipe for a lot of stuff to be ignored. The previous agendas that might have been the first step in a fine program of ideas that would lead to wonderful things becomes The Agenda. Predictably, the first step isn't enough to see a whole lot of fruit so...yeah.
Third warning -- we weren't allowed to even talk about creating new products. We're an acquisition company, now. We buy winners. We don't risk creating losers. Not so fun for someone who Really Loves Creating New Things.
So...here I am envying your early clarity. Large companies are just different. I am starting to believe innovation at scale is rare, if it exists at all. If I were you, or me two years ago, I'd start looking for a better fit.
Let the MBAs run these companies through the motions of the terminal stages of the business lifecycle. I'm ready to get back to bringing new things to life. It sounds like you are, too.