The K-1 interview can be used for the disposition  OR   the 1099-B  but just  don't do both. 

The issue is Final k-1 to be checked you have to enter the Proceeds, date of purchase, date of sale , cost of sale, Cost basis in K-1.  you should not enter it in 1099b or you will be double taxed and will not take advantage of other offsetting benefits in K-1.

we can't see the K-1 or 1099-B.  normally the K-1 would only report your share of the S-Corp income/loss for the current period and not your sale of the S-Corp stock (especially so since it was not the S-Corp that bought it).  the 1099-B needs to be entered in the 1040 because the IRS gets a copy (it also gets a copy of the k-1). your tax basis might or might not be the same as the proceeds.  the 1040 form 8949 is supposed to reflect your tax basis. since it wasn't supplied you are going to need to determine it. it is highly unlikely that you have no gain or loss from the sale of the stock. 

1099B

From a previous post in Intuit – We put the cost basis to be equal to the proceeds so that the 1099B would show zero gain. don't where you saw this but in your situation, it is highly unlikely this is correct.  since you got a 1099-B that's where the sale price and cost are supposed to be reported not through the k-1 disposition worksheet. 

As noted by @Mike9241 we can't see any details, however, my thoughts are as follows:

• As noted in another post, you do not want to duplicate the information in two places which could result in double the gain.
• In my mind, entering the 1099-B info to arrive at a zero gain or loss makes sense if you are entering all the sales information in the K-1 interview process.  Doing this will arrive at the correct answer and be reported in the correct area of the tax return.
• In cases such as this, handling the final K-1 current year details and sale matters in the K-1 section is a cleaner process.
• The above assumes you know what your tax basis is in your S corp stock.  This is needed regardless of how you enter the information into TT.
• As you noted, the IRS is only receiving the proceeds figure on form 1099-B and that is all they are looking to match in their system.  As a result, you do need to reflect this figure on form 8949 which will carry to Schedule D, but will result in a zero gain / loss as noted above.  This avoids any matching notice.