W.S. Bro it's the same thing which I experienced.
I called helpline regarding this issue. The guy said that FBR has not started tax returns filing for the year 2017-2018. It will start somewhere in the month of August, 2018.
He further added that template / draft for filing tax returns for the year 2017-2018 might be different from the previous years, so there is no use in saving the current draft and it may be discarded.
So Bro, it's better to wait for the official start of filing of tax returns. When they start (and it will be advertised in the daily newspapers), only then we will be able to file them.
I hope, it helps. Thank you.