We're Still Waiting to Find Out What Happened Off Farsi Island Last Week

A week after two Navy boats were taken into custody in Iranian waters, the Pentagon still doesn't seem to have any idea what happened:

[The two boats] were supposed to follow a course that would keep them in international waters. They were scheduled to refuel at a rendezvous with the Monomoy, a Coast Guard cutter, at about 5 p.m. But the two boats veered off course Into Iranian waters.

....The crews then stopped to try to fix a mechanical problem in one boat’s diesel engine. “This stop occurred in Iranian territorial waters, although it's not clear the crew was aware of their exact location,” the report said.

At about 5:10 p.m., one of the boats apparently sent a brief radio report that Iranian boats were approaching. A second message was garbled. All communications were cut off by 5:45 p.m., the report said

This is all still pretty peculiar. On a trip from Kuwait to Bahrain, all these boats had to do was stay within 60 miles of the shoreline and they would have been fine. Why were they so far out? Where was the Monomoy? Did they really suffer an engine failure, two GPS failures, and two comms failures all at once? I know that a thorough investigation can take some time, but this one doesn't seem very complex. What the hell happened out there?