Some users have reported that the cost basis associated with a transferred lot is incorrect. This can happen when timestamps of a Transfer matches another corresponding transfer, or when using the linking feature to combine a Send and Receive transaction.

This can also happen when the timestamps of the Transfer for each wallet differs from each other.

You can also upvote this forum post to indicate you are experiencing this behavior. The post status will be changed to once a fix is rolled out to all users. Up-voters will be notified of the status change.