If you gain was less than your exclusion ($250,000, or $500,000 for married filing jointly), Turbotax will ask something like "you don't have a taxable gain, do you still want to include the form yes/no". You should always include the form if you get a 1099-S from the IRS because they are going to want to see the information even if it is not taxable. If you got a 1099-S (so the IRS knows about the sale) but you did not include the forms (you checked "no"), the IRS won't have the backup info and will think the sale was taxable.
Go online and download the PDF for "all forms and worksheets", there should be a form 8949 and a schedule D, or there may be a "home sale worksheet." Or in the desktop program, go to forms mode and print form 8494 and schedule D. You can send these to the IRS with a letter of explanation that you qualify for the exclusion and your gain was less than the exclusion, so your tax software did not include the sale. But the documents will be the supporting proof that you don't owe tax.
If you don't qualify for the exclusion or the gain was more than the exclusion, then I would call customer support and start looking into it. You always owe your own correct tax, but if Turbotax made a calculation or forms mistake, they should cover the interest and and penalties. Here is a link to file a claim,
https://ttlc.intuit.com/turbotax-support/en-us/help-article/account-management/turbotax-100-accurate...
