The Undefined setting was an attempt to make the code more generalised, It worked fine on a few cases I tested it with before posting it, but i might have just got lucky (or unlucky...).I thought that having ViewDetailLevel set to Undefined would provide the full set of geometry from which to find the matching face no-matter what the setting of the view where the selection was made.Maybe that's not how ViewDetailLevel.Undefined works. if it is as you say and it signifies to only return geometry that does not have the detail visibility override set, then to fix it, I would loop through on each ViewDetailLevel setting until the geometry was found. thanks for testing it out and giving a heads-up. btw, which documentation mentions "ViewDetailLevel.Undefined means no override is set"?, I just check and the docs say "View does not use Detail Level " which I think means something completly different to both mine and your interpretations, odd.
out of interest have you changed the code to include the view in the geometry options? if so, does removing it help?