Pure speculation incoming: probably a completely unintended bug. Classify as static, static objects shouldn't have tracks, clear the history. Your object is reclassified as dynamic, whoops, we already cleared the history, oh well.

Static is not a classification; in this case the classification was cycling between "unknown", "vehicle", and "bicycle", and each time the classification changed the history was reset. Then each detected object can be either static or be assigned a predicted path, but unknown objects without a history are always treated as static.

In any case, the history clearing seems to be a bug, they updated the software to keep the position history even when changing the classification.

In your example "unknown" is implicitly "static". Either way, neither of us have access to Uber's source history to say what exactly went wrong. They do claim to have fixed it though, you're right.

Strange that the history itself is not used for the classification.