Not a carrier revising its own estimate, which is normal, but the same event reading 24/03, then
30/03, then 24/03 again across successive updates, without converging.
Example
A container’s event date appears as a value in an update, changes to a different value in the next update, then returns to the earlier value in a later update. Across successive updates, the same event keeps alternating between those values and never converges. This is not the carrier revising its own estimate; the event reading itself is inconsistent from update to update.