@jonodempsey That sounds frustrating. I’ve had success in the past reaching out directly to Facebook support and going through the process with them. Here is a great place to start: https://www.facebook.com/facebookadsupport

Let me know if this works or if you find another solution!

Thanks,
That’s what I figure I’ll have to do, but am hoping someone else has had a similar experience. 
Thanks for the link! 

Had a similar experience.  We were admins on the page as a Partner, but not an admin on the Page directly.  We were unable to see who actually had access since we only had Partner level admin rights (Facebook support couldn’t tell us either) and no one from our clients business actually knew who was on the account.  We ended up opening up a support case and they gave us instructions on how to request admin access which required getting a written letter from the organization proving our relation to the business and submitting it to Facebook support through an email thread.  I hope by knowing this it helps speed the process up, it took us months of various facebook chats/phone calls and support emails to get to that point of sending the letter.  

Hi Lauren, Thanks for sharing your experience!

I’m still working through this, and hope to have it resolved soon. If my current plan doesn’t work, I'll be sure to try the above. Hopefully we won’t have to go to such lengths.