I have the exact same problem. I have no issue with other RSUs, which I got more than 1 shares vested. The only problem I have was vested 1 RSU and sell this right away for covering tax. The tax calculated seems right, as i am not double paying the tax here as far as I can see. but this error keeps bugging me... And as mentioned by other people, you can ignore this and e-file, and this is what I choose..
P.S., I have manually correct the cost basis as mentioned by other folks below. Still having issues with this exact 1 RSU vested/sell. There is definitely something wrong with Turbo tax here.
