Took me 5 months to figure out why my chain kept dropping on the Fremont bridge approach
Turned out my rear derailleur hanger was bent just enough that it only slipped under load on that one steep ramp, and a $12 alignment tool from a shop in Ballard fixed what three new chains and two cassette swaps could not, so if your gears ghost shift only on one part of your route, check the hanger first, anyone else chase a gremlin like this for way too long?