Yes, see here: http://www.flysas.com/en/EuroBonus/S...liance/United/

Earlier this year, I bought an SAS Fully Flexible Economy Extra ticket through the SAS call center. When I tried to check in for the United portion, I ran into this mess. I got bounced back and forth between SAS ("It should be premium economy" / "There's nothing we can do - Go talk to United") and United ("S is a heavily discounted ticket" / "You'll need to pay $50 for Economy Plus" / "We don't have any kind of premium economy cabin - Economy Plus is an add-on option to a regular economy ticket").

If you're Star Alliance Silver/Gold, they might put you in Economy Plus, but they have no obligation to do so.

What's worse, that flight showed up on my EuroBonus account as a United Low Economy fare, which means I got 25% points for it, even though I paid SAS Fully Flexible Economy Extra prices for it. SAS fixed it up after I wrote them an angry letter