Victor - you ask a great question. First of all my suggestion to talk offline is so we can discuss things offline that would not be appropriate for this forum. Hard to help without more information.
At some point, you or the property manager entered into a contract with section 8. You authorized that manager to enter into this agreement as your agent (I am assuming you had a property management agreement in place authorizing your property manager to act on your behalf). That manager rented your house to a section 8 tenant, took the house through the inspection process, brought the house in compliance with Section 8 requirements, and entered into a contract with section 8.
I have found the section 8 department in Charlotte, NC to be reasonable but firm. If I have had issues with an inspection, I have picked up the phone and called them or have sent an email to my department contacts. It might take a day, but I will get a response. As a Landlord, if I do not uphold my side of the agreement with Section 8 as committed, rent stops. It is that simple. And what is required is that I provide a home that is safe and meets reasonable requirements for a rental home.
My guess is your property manager did not uphold their side of the agreement. There might have been an inspection requiring repairs and those repairs were not made in a timely fashion, resulting in a rent abatement. If rent abates then you have a short window (I think it is 30 days) to pass an inspection and if that inspection is not passed, the tenant is required to move. Section 8 in Charlotte in particular has recently been much stricter on these deadlines so I would not be surprised this is what has happened.
In terms of your recourse against the previous manager, good luck. I will tell you that good third party management companies are hard to find. They are out there for sure, and as the owner you will have to be hands on in the management of that relationship. There is information you need to know beyond the financial reporting. Know your rent roll, status of each rental, what type of tenant, etc.
Ask questions and expect answers. You don't have to be a pest - your manager just needs to know that they will be held accountable for the management of the property. Can not be hands off in management of your property manager. There must be accountability in that relationship, otherwise the manager will focus on matters that seem to be higher priority than your unit. Trust me... you have a LOT more to lose than that manager if a unit goes vacant.
Glad to continue discussion. Good luck in getting this matter resolved.