If the cars were able to---albeit slowly---cope with the closed streets through this kind of cumbersome queueing in a dead end and turning around, it seems possible that Waymo might not have been aware there was an issue.
They're aware. When they were made aware it doesn't say, so maybe it's just recent. But the problem's been ongoing for a while it sounds like.
EDIT: The cars have a safety driver, i.e. there's a human in the loop. No excuse for Waymo to not know about this basically immediately.
I’m this is a like a tech variation on “if a tree falls in the forest, and no one hears it, does it make a sound?”
Or even a “amount of time to complete trip” vs “predicted time”.