Your best option is to terminate the current manager and switch to one with better processes and communication.

Absolutely no communication. 

The communication was prompt.

@Aaron Zimmerman please correct me if I am wrong. 

The property is held in an LLC taxed as a partnership...one partner wants out, another wants to refi and buy them out...no formal operating agreement, just a handshake and some rough P&L splits over the years.I've been working on deliverables to show the potential gain recognition if one partner cashes out and how to allocate basis correctly across the remaining partners.

Let them know you will hold them financially responsible if they fail to follow your instructions and that you may file a complaint with the commission.If they refuse to communicate or act, file a complaint with the commission.

If this is private lending and there is no note and mortgage prepared or your lender keeps a deed in trust, depends on state, then I would absolutely find a good attorney to make sure you have all the correct paperwork done and then also involve your title company so the transactions can take place all together and the new loan can pay off the existing loan. 

First, if I understand correctly, the syndication made no distributions at the time because money needed to be spent to develop management capabilities for the sponsor.  

Based on your description, I would likely accept this applicant, but with clear communication and safeguards.

I have been proactive in communicating my frustrations and lack of communication from the builder to the seller for about 9-months now, but no follow up has been received from the builder.