So I was picking seats today for my ORD-AMS UA908 (3/20), and was able to pick 23b. Now, these tickets were purchased from expedia, and it's marked as fare class S on the UA itinerary site. I looked this up in the handy booking codes thread:

S = Real Lowball coach with lot of restrictions. Reports that some are not mile earning ex UK/Brazil etc.

I'm also aware that non-elites (me) are unable to preselect E+ seats. How am I able to do it now? A day ago, the only open seats were in E-, and when something opened up in E+ I jumped.

Some more background, this is a 767-300, and according to the UA seatmap compared with one on seatguru, it's the new config. Any ideas? Will I just be bumped back to E- at checkin, but now without a preselected seat?