If it was a communications error any responsible action would have been to surface immediately, there is no way they have the reserves to sustain more than a few hours extra past their 10 hour planned dive.
If their protocols did not include an immediate mission scrub on loss of comms they are grossly negligent and the company is toast legally, not just financially but a case could be made for incompetency and even negligent manslaughter. Deep dives are literally that extreme.
Let us pray that they are just incommunicado for now, and still safe.................