While they've provided decent cash flow, the recent maintenance demands have been significant, with one tenant move-out leading to a $20k+ rehab and new appliance/HVAC costs. 

In other words, it’s income that you earn passively with minimal effort and involvement.Strategies To Generate Passive Income1.Rental PropertiesRental properties can provide a steady stream of passive income through rent payments from tenants.

I am wondering if it puts you on the hook as the contact in case of emergency or violations.I would call the CBP and get the skinny on that before I provided the phone number.https://i94.cbp.dhs.gov/I94/#/home

An additional benefit of a detailed engineering-based Cost Segregation Study is that it can increase potential insurance premium savings as well as provides support for the property tax appeals process.

Historic tax credits can indeed provide significant financial incentives for rehabilitating and preserving historic or non-historic buildings, promoting the conservation of our nation's architectural heritage.

Neither bank didn't provide any explanation of what terms I and my loan didn't pass. 

Are there any examples you can provide please?

There are a number of people who post here who will likely provide way better bang for the buck. 

Real Estate is too much fun and always a good safe place to stash your money...plus you're helping to provide quality housing for your neighbors.So do you want to play it safe?

There are some lessons that can only be learned through experience, and A HH will provide incredibly valuable lessons that no mentor, real estate course, book or podcast could ever teach (though, I'd still recommend reading up on relevant RE resources, listening to podcasts, etc.).