Do you still have the 2016 program on your computer? Try saving it again from 2016. Does it have a password on it? Take off the password and save it again.
I found this answer....
Then with 2016 running and you can see your data, do a File -> Save As (hold the option key down) and save a new xxx.tax2016 file to your desktop or where you can find it and try transferring from that. I know of no reason that it should not transfer the data.