I was told by someone in the auditor’s office that a sale wouldn’t trigger a reassessment.  

Honda has invested $3.5 Billion in Fayette County for a plant that will make batteries for electric vehicles. https://www.dispatch.com/story/business/automotive/2023/02/28/ev-battery-plant-in-fayette-county-to-employ-2200-workers/69933524007/According to Licking County Auditor records, Amazon Data Services Inc.

You can use the major real estate sites, the local auditor, and ask a local real estate agent. 

Therefore, unless you combined all rentals into one activity, they expected you to pass this ridiculous threshold per property, and even the Tax Court made erroneous decisions against the taxpayers using this flawed argument.While they finally figured it out by now, and the Court has started applying the law correctly, many IRS auditors and even IRS attorneys are still under the old 750 hrs per activity thinking.

Why else would companies hire out 3rd party CPA auditors to audit the books even when they have a CPA as the controller/cfo?

Unfortunately, East Cleveland is a bankrupt, Ohio Auditor operated municipality struggling greatly to operate very basic civic services. 

I've already used the county tax auditor to find the LLC the property is under.

I would also make to check the auditor to see what the taxes are and consult an accountant or tax adjustor to estimate what taxes might get re-assessed to.

Depends on your county...Google "Your County" auditor, or recorder.

A good way to find landlords is to check with the county auditor.