I’m not sure if I deleted the blend before or after the split, but I was able to make a neighboring srf on the first segment. Now it shows two complete edges. BlendSrf couldn’t use it.
It happened again on another surface. I haven’t nailed down steps to reproduce because it doesn’t show up immediately. It’s something about a full or partial edge being used with blendsrf prior to the edge being split. Maybe edge split should break history?
MatchSrf was also involved both times. Not sure if it’s connected.