Can anyone cite a IRS rule or ruling, or any other official IRS indication, or even a private sector legal or accounting or other expert opinion, or any other supporting evidence, that accuracy of the broker's 1099-B doesn't matter?
Hey nincompoop... problems abound with 1009-B's in general.
IOW, not specific to YOUR description of what YOU deem to be a problem...
http://www.tradelogsoftware.com/pdf/The_1099-B_Problem_Special_Report.pdf
https://greentradertax.com/dont-rely-on-1099-bs-for-wash-sale-loss-adjustments/