Can't know for sure until TTX implements the final Nebraska forms on/after 30 January.
Come back on 31 January, edit that particular 1099-R form (CSA-1099-R?) in the federal section, and see if there is a follow-up page allowing you to select that US pension for exclusion form NE taxes. If not there, then there may be some new questions in the Nebraska interview section that allow you to eliminate that income from Nebraska.
But, likely not until after 30 January, when the NE forms are finalized.
____________*Answers are correct to the best of my knowledge when posted, but should not be considered to be legal or official tax advice.*