San Diego flood victims are being provided permit amnesty so that previously unpermitted work can be rebuilt.It is interesting that if your property has unpermitted work, the city is providing amnesty so that the property can be rebuilt as it was prior to the flood.  

Know your local zoning laws, building codes, and licensing/permitting regulations.2. 

I'm willing to travel to Miami once or twice a year and manage the properties from Spain, hiring a good property manager to address issues, find new tenants, manage payments, and clean the property for new tenants.

It is a recurring issue that will come up whenever new tenants move in or out.

Dealing with frequent lock issues can be a real hassle, especially with multiple units.

Also, you are offering way too much, not sold for a year, ok it has issues. 

But that increase can come with a thorny issue: capital gains tax when they file their tax returns after selling.

Actually he brought the issue to your attention, was absolutely correct and the best thing you can do is make a note of it for the future. 

Somehow, it seemed to blow up as an issue during Covid. 

Sounds like a hard money lender that wants to take a property from you when you default.There's a lot of issues here starting with a guy that will loan you money and once it gets difficult wants you to abandon ship- red flag.There are a lot of unknowns here but trying to dump it seems like a 100% guarantee to lose money.