Following may be the reasons:
The reserve price may be higher. If the bidder doesn't meet the lot's reserve price (automatic minimum), bidder may try outbidding the earlier bids.
An automatic bid is outbid then the bidding history will reflect the 1st and the final step of the user's automatic bid in a row. The final highest bid will be automatically shown at the top most of the bidding history.
The icon **** showing as automatic bid means a higher suspense bid placed by the bidder.
Automatic suspense bid minimum winning amount/bid will be the reserve price only.