Are you talking about Absolute or Relative accuracy?
The default shtmtl templates (startpart) in Creo has an absolute accuracy of 0.0125. I tried changing this as low as possible which was 0.0033 but it's still failing.
The feature acts very strange. I created a rectangular planar with three chamfers.
I edit the Chamfer feature and add a fourth chamfer.
The Flange Wall feature fails.
I edit the Flange Wall but all references are valid. I also checked that they are in correct order, by switching from rule-based to standard, and they are.
If I delete the Flange Wall feature and recreate it again with the same references, same edge and surface, it works....
