Okay here's what's happening step by step.
1. Align parent surface to other curve or surface
2. Trim surface setback to create blend, history active.
3. Align blend to trimmed edge ("edge align" used on both sides).
4. Try to untrim parent surface again to align another adjacent surface to its full theoretical.
5. History notification pops up requiring to delete history (only history on surface is that original align).
6. Click okay, parent surface no longer aligned, blend no longer aligned.
***Note, this does not happen when "skew" used on blend surface edges. I can freely untrim parent surface and history is sustained. It seems like the system doesn't want to think about edge aligning to a another surface when that parent surface is aligned to something else. Pretty annoying, I think!
Not sure if this is a purposeful feature or a bug. Thoughts?
