The answer is relatively simple, it's landlord fatigue.  

His reason was the only thing he knew to do with the proceeds was to loan it back out at 12%, and he would be "behind" where he is now in cashflow.His proceeds would have given him options up to and including PE, but he is a simple man and in his case holding was the option for now. 

They used to be good and simple. 

I also agree that RE appreciation is unlikely to match the last dozen years, but you never know.Where I am unsure we agree is that paying $450k to improve the cash flow ~$3k (your numbers but I expect my delta wold be similar meaning both my cash flow estimates would be worse than yours but both would be worse by the same amount not affecting the difference) makes sense especially if the cost of having the extra $450k is only 6% rate which is historically simple to beat via numerous investment options and hopefully no one is investing in RE for an expected of 6%.  

Keep it simple - sell the property and let each sibling do what it is that they want.If you keep it and do a refinance(to pay for the bills)Who will be on the loan, will it impact everyoen's DTI?

Do you still recommend using a real estate CPA or is their tax professionals that specialize in the more simple investor situations like mine?

Simple, reasonable action and patience. 

This can be as simple as an excel spreadsheet.

With software, it's only as powerful as its user so some clients overcomplicate things and spend most of their time trying to "fix Quickbooks".The most successful and quick clients keep it simple or keep it to their comprehensive level. 

Brown: I use https://www.bestwyomingregisteredagent.com/Very simple, 100% online, they are responsive if you need help.