If you have any friends on the "C" level or "EVP" level, I'd go there. HR is not going to be of any use to you. They are there to protect the company's interests, not yours.
The only way to get to the bottom of this is to go to someone who has some actual power in the company who can lean on HR to release the information or remove the black mark.
Talk to the manager who wants you and ask if it would be OK with her if you inquired at higher levels. If she says "no" then drop it.
It might also be time to drop it.
Sadly, this is not uncommon for larger companies, which is why so many larger companies bleed talent.
Whenever an organization becomes large enough to require a bureaucracy, it is the one who is most skilled at navigating the bureaucracy that gets ahead, not the one with the most talent. This seems to be the case with you. Someone more skilled in the bureaucracy has put a roadblock in your way.
Don't push too hard though. As your lawyer said, you have a right to know, but not a right to a particular position.
( 7 months ago )
I was at a company for nearly 15 years (Let's call it BlueTech). I had been through many bosses. 2 years ago, I got a particularly bad one and happened to have an opportunity open up at another company, so I took it. I technically only reported to the new boss for a week tops before leaving BlueTech.
I worked for another company for 2 years.
Now I have a great opportunity for another job at BlueTech. The hiring manager wants to hire me, but she never received my application. I found out through the grapevine that I had been "blacklisted". It's been 5 business days. I've made dozens of phone calls to various people, sent lots of emails, etc and I still don't have an actual reason (or really even official confirmation). Meanwhile, the job will have to be filled soon. I'm going to miss it.
The one HR person that actually responded, I asked that she look at my last 5 or 10 annual reviews. She continually says "former coworker eligibility" isn't her area, but she won't give a name to contact. I've left voicemails with the person I think is responsible for eligibility, but no callback.
I suspect the reason is that they accused me of "stealing" some source code. However, I have screenshots of a conversation from 2 years ago with a coworker in which he revealed this accusation and then laughed about it stating he (and "they") DO have access to it (it was hosted on BlueTech servers). He is still on the same team.
I briefly talked to a lawyer, but the only "right" I might have is to find out WHY.
After 15 years there, I have lots and lots of friends. This is really blowing my mind.