Did they discover something that was going to potentially cost more than they thought?

Also if it is intended to possibly be a rental you should calculate the end result of the acquisition, the debt service, the rehab, etc and pretend to get a loan to refinance. then look at the potential rent to offset that monthly cost and see if it would cash flow.

Let me know if you have any advice for organizing expenses and projects to stay up to date on the health of the property. 

Knowing this information will help you identify the right professionals to bring on board.At minimum, your team team should include:Financial Advisor: to help with investment strategies - portfolio diversification and risk management.Real Estate Agent/Broker: to help with property acquisition and market analysis.Accountant or Tax Advisor: to help manage financial records, tax planning, and optimization.Attorney: to provide legal counsel for contracts, agreements, and investment structures.Mentor or Coach: to offer guidance, insights, and industry knowledge.Networking and Relationship Builder (for everything else you will need): to connect you with potential partners and collaborators.

He didn't have much downside in terms of potential losses, and I could be somewhat passive and protected legally (he owned the building site etc. and took care of liability). 

but that's not investing.I've been making offers on potential BRRRRs this year and getting turned down. 

It is tough to crack, but it has so much potential. 

Quote from @Preet Sekhon: Just wanted to flag something potentially impactful for real estate investors: it looks like 100% bonus depreciation might be making a comeback next year.

This might be my key question, as eviction itself doesn’t worry me as much as the potential hassle it might bring. 

If this happens, new people won’t be able to get vouchers, and landlords may have fewer potential tenants to rent to.