We have discovered a bug in the Massive Replace feature, which was new in Gemini Terrain version 18.1. The error means that attributes get incorrect values, and the function must therefore not be used. The ordinary Substitute function is not affected by this.
The bug has been fixed, and the fix will be available in Gemini Terrain version 18.2, which is scheduled to be released in June. If desired, you can contact us at gemini@volue.com to access the beta version of Gemini Terrain 18.2 in the meantime.
We apologize for the inconvenience this may cause.