Eligible for rehire upon leaving company but 10+ yrs. later, somehow now ineligible & cost me a job

I left a company in Feb 2008 and at that time, I verified that I was eligible for rehire. In 2014, I asked a friend in my former company's HR to verify my eligibility for rehire, and it was confirmed that I was. In 2015, I interviewed for a position with my former company and went through entire interview/selection process (another candidate got position). In 2018, after applying for multiple open positions with former company, another separate company to which I applied called to tell me they couldn't consider me since, upon contacting my former company, I had been reported as ineligible to rehire. I called my former company to verify and they told me that I was ineligible now. I asked why and the directed me to fill out and email inquiry form which I did and despite following up twice over the past 8 months or so, I never received any reply.
I left my former company on good terms (resigned to accept another position) and verified I was 'eligible to rehire' yet 10 years later, after applying for multiple positions with my former employer, I am all of the sudden no longer eligible. It cost me a position I really desired at the time and I'm concerned it could occur again.