Validate their Legitimacy:Ensure the company is properly licensed and regulated, particularly if you're working with private lenders.

I have flipped new homes and townhomes but phased out raising a family and now am focused on utilizing my skills which are building, selling, expanding a circle of influence to focus my effort on the above.

So, not a good look.I do like that you guys encourage due diligence and 3rd party inspections to insure work is done properly.  

that we’ve learned in our 24 years, managing almost 700 doors across the Metro Detroit area, including almost 100 S8 leases:Class A Properties:Cashflow vs Appreciation: Typically, 3-5 years for positive cashflow, but you get highest relative rent & value appreciation.Vacancy Est: Historically 10%, 5% the more recent norm.Tenant Pool: Majority will have FICO scores of 680+ (roughly 5% probability of default), zero evictions in last 7 years.Class B Properties:Cashflow vs Appreciation: Typically, decent amount of relative rent & value appreciation.Vacancy Est: Historically 10%, 5% should be applied only if proper research done to support.Tenant Pool: Majority will have FICO scores of 620-680 (around 10% probability of default), some blemishes, but should have no evictions in last 5 yearsClass C Properties:Cashflow vs Appreciation: Typically, high cashflow and at the lower end of relative rent & value appreciation.

Agree with @Jake Baker—real estate is very balance-sheet heavy, so working with a bookkeeper who truly understands a balance sheet, the industry, and how to structure QBO properly will save you a ton of headaches down the road.

Any advice that can be shared to try and get over this hurdle to be able to expand our portfolio? 

One of the biggest challenges for everyone involved is being on the same page about the actual time required for maintenance.DIY landlords rarely properly track their time when it comes to property management in general - tracking their true time invested in maintenance is where they perform the worst.Investors that hire PMCs are rarely any better at understanding the true amount of time maintenance takes.

I've realized that embracing all types of Investors and expanding my Network in every way aligns with my Goals and benefits the Investing Community as a whole.

Proper underwriting is important.  

There are fees associated with going to Real Estate school, obtaining your license, joining the board and MLS for your area, getting proper E&O insurance and so forth.