This poll has Sanders at a 44% favorability with 18-29 year olds and 27% not sure LOL. Did they try to push the undecideds at all?
27% undecided among 18-29 year olds isn't that unusual. PPP, for example, regularly has polls in which the 18-29 undecided number is high on everything. E.g., look at this poll:
http://www.publicpolicypolling.com/pdf/2017/PPP_Release_National_82317.pdf64% of 18-29 year olds are uncertain on whether or not they have a favorable opinion of Russia, to take one of the more extreme examples.
