No, this is probably correct.
The issue is this:
The processing of the original return is done separately from the processing of the amended return. Your 2017 refund is being processed (or would be if the IRS hadn't flagged it) and at some point, if they release your return, they will send you your $7,500 refund.
The amount of $869 on your amended return is over and above your refund on the original return. That is, the software determined that if you had filed with the 2017 W-2 originally, your refund would have been $8,369. But since your $7,500 is already coming to you as part of the original filing process, the amendment will send you only the difference.
Go ahead and finish and mail the amended return. If in the meantime, the review team sends you another letter, just reply that at the suggestion of the Taxpayer Advocate Service, you filed an amended return to correct the issue you know about. With luck, that will settle things.
Of course, the review might discover something totally different which might mean that you would have to file a second amended return.
