How to handle attorney relationships during negotiations

My team has been negotiating a deal with two owners of a very profitable and well-run hair salon in the DC area. We have been under exclusive LOI for about 45 days and are in final negotiations on a purchase agreement. During due diligence, sellers and broker were extremely collaborative and responsive, sharing files, logins, etc. Financials were spot on and all parties seemed eager to work together. However, everything changed when the attorneys got involved. Once a draft of purchase agreement reached the seller attorney, all communication seemingly stalled completely. There was one particular clause their attorney took issue with--an indemnification escrow of 10% of the purchase price--and he refused to review the rest of the document until we removed it entirely (we don't want to remove it until we have full comments and can agree on the rest of the terms). Even the sellers' broker admits it was very standard contract, but the seller attorney has taken over all communication. The seller attorney is not a deal lawyer, but rather a litigator and family friend to the sellers and he has been incredibly combative, unresponsive and taken the negotiation personal. Unfortunately, he seems to have the ear of the sellers, as my communication has been cut-off with them. Both of our attorneys have advised us (buyers and sellers) to not communicate directly with one another and rather let the lawyers handle the back and forth, but ever since they "took over" the tone of negotiation has turned negative and has slowed to a standstill. Does anyone have any experience with deals that fell through due to attorneys who could not come to an understanding even when the buyers and sellers seemed willing to make it work? What is in my power to do to restore trust between all parties? Thanks for sharing your stories and experience!