I'm a research fellow on a J1 visa, my DS2019 exchange visitor category is as a "Research Scholar." I was in the US for >11 months during 2018. Am I a tax non/resident?

[Opus 17]

J1 scholars are considered non-residents for the first 2 or 5 years of their education program.  (I forget which and I'm too lazy to look it up.  Your school's international student office should be able to help.)

Turbotax does not prepare a 1040-NR non-resident return.  You will need to find another tax preparer or software company.