Hi,
I manage 9 Facebook Pages - this is very common and this is issue is something that, according to my experience, should not be complicated nor should it take too much time.
It’s very easy to claim a Facebook Page as long as the owner of the brand / business that represents the Page is the same person that is claiming it.
This issue tends to happen when someone by accident claims ownership of a wrong page or (what happens the most) when a Location is created by Facebook automatically when people create check ins, reviews - then it automatically becomes sort of a Community / Location that appears to be a Page but actually lacks Administration.
I’ve done claims like this at least 15-20 times and I’ve managed to regain Admin Roles.