Sorry but the LL royally screwed up and now is paying the piper for being a completely absent LL.

Don’t look at only their managers fee, ask what the average client pays in total fees (monthly, lease up, extensions, etc) as a percentage of rent collected.

Do you recommend I just pay it? 

The property is still your responsibilityBuyers will claim to sellers that they no longer have any responsibilities and that the seller doesn't have to worry about paying the mortgage fixing the property or taking care of expenses.

That is not an issue.the question is how to coordinate the two sales and one purchase. if it’s too complicated, may just pay the capital gain tax.Quote from @Bill B.: You lost all hope at step 1.

Do you think at 7% DSCR it is even worth it, considering the fourplex will essentially just pay off its own mortgage + taxes and not have any leftover?  

Move into the triplex for two years and use IRS Publication 523 Sale of a Residence to not have to pay some of the Cap Gains when you Sell.

I'm paying very high monthly fees and additional management/service charges but am still not getting the help/education I would like.

Purchase price: $585,000 House hacking my first SFH - airbnbing the basement that has a separate entrance and my partner pays me for rent How did you finance this deal?

A "seller" like you would pay that up front.