The way I read it was, everyone was going to be there, there was a problem with/in the tunnel (I dunno, maybe with power to booths or something?) so they had to hang back for an hour, but all arrived in the end.
But then there's this counter from our side, so...
"It's “absolutely not the case” French border officials were unable to deploy at full capacity in Dover because of an “unforeseeable incident” in the Channel Tunnel this morning, Eurotunnel's Director of Public Affairs John Keefe has told the BBC.
“The incident at the port started overnight well before a minor technical incident in the Channel Tunnel. There is absolutely no correlation between the two," he has said.
He wouldn’t go into details on the tunnel incident, which is thought to have started around 7am this morning after the Port of Dover declared a critical incident, but said it did not last very long and “only slowed traffic down; it didn’t even stop traffic”.
“It had absolutely nothing to do with problems at the Port of Dover,” he has said."
It's all here -
https://www.bbc.co.uk/news/live/uk-62260474
Neither side comes out of it looking great to be honest. Details are all a bit light on the ground.