Is this a 1099-MISC or a 1099-B?
A loss on personally held cryptocurrency is never tax deductible. Cryptocurrency is treated by the IRS like personal property—a car, furniture, or baseball card collection. When you have a capital gain (you sell for more than you paid) you owe tax on the gain, but when you have a loss (you sell for less than you paid), losses are not tax deductible.
Losses on cryptocurrency held for investment may be deductible, if you can convince the IRS you were an investor and not using the cryptocurrency for personal purposes.
If you got a 1099-B (B for "broker") that shows you lost money, you should enter that on your tax return because the IRS will be trying to match any 1099s you get to your tax return. However, I believe there is a box to check in Turbotax for "this was personal property" that will stop you from deducting the loss.
Or, you may have gotten a 1099-MISC for $89 of income. This is not taxable, because it's actually a loss, but again, the IRS may come looking to match the 1099 to your return. What you would do in Turbotax is enter the 1099-MISC as other income, then create an offsetting item of other income in the amount of -$89 with an explanation like, "offset income from item sold for less than basis".
Now, because you didn't include the 1099, it would be best to amend. But, amending your tax return will not change the amount of tax you owe or give you a refund, and in this case I believe Turbotax online will tell youy that you don't need to amend and will refuse to actually print an amended return. You can print an amended return using the Turbotax desktop program, but if you don't already have a copy installed on your own computer you will have to call customer support and ask them to put a copy in your account (assuming you already paid for Turbotax online).
Lastly, you might consider the alternative of not amending, and keeping your documents and other proof on hand for at least 3 years. If you have a 1099-B showing an $11 loss, the IRS is unlikely to send you a letter telling you that you may owe less tax. (They take, they don't give.). If you have a 1099-MISC showing $89 of income, you may get a letter, but you can reply with proof of the transaction and and explanation of why the money is not taxable (personal item sold at a loss).
