On Monday morning, the Islamic State fighters had agreed to pull out of a 27-square-mile enclave they held on the border between Lebanon and Syria, near the Lebanese town of Arsal, in a deal they cut with both governments, and with Hezbollah militiamen from Lebanon who are fighting alongside the Syrians. Under the deal, Lebanon received the remains of nine soldiers taken prisoner by ISIS in 2014; the ISIS fighters received free passage to Deir al-Zour, 300 miles to the east.

From the beginning, the convoy encountered problems. Instead of heading due east, it turned north and to the city of Homs. There it transferred to buses and ambulances reportedly sent by the Islamic State and then headed east Tuesday morning. For some reason — possibly concern about airstrikes — what would normally be a 10-hour trip took most of the next two days.

Throughout, Islamic State media outlets have been unusually silent about the deal to give up Arsal, the last significant ISIS enclave on the Lebanese border. For the militants, who normally pledge to fight to the death, the optics were humiliating. Video posted online showed busloads of militants, many of them covering their faces with their kefeiyah scarves, driving through lines of Hezbollah and Lebanese army fighters who waved flags and laughed at them.

Rita Katz, head of the SITE Intelligence Group, which monitors ISIS and other extremists online, said that ISIS supporters refused to believe the Islamic State had made the deal to evacuate. She said, “Some users on a pro-ISIS chat group called reports of the event ‘Fake news,’ asking, ‘Since when is news from Hezbollah authentic?’”

Al Akhbar, a newspaper in Lebanon that generally supports Hezbollah, reported that Islamic State forces in eastern Syria were upset with the convoy’s occupants for abandoning their border enclave. They did so after an apparently coordinated weeklong offensive against them by the Lebanese Army, Hezbollah and the Syrian Army, which had surrounded them.

Once the convoy was blocked in Humaimah on Wednesday, it apparently had to negotiate permission from the Syrian regime and its Hezbollah allies to try another route. Hezbollah demanded that the ISIS militants turn over the body of an Iranian fighter whom they had killed, the Reuters news agency reported, quoting the Syrian military source. It was not clear if that was a new deal, or part of the original deal on Sunday.