This is the log entry:
[02:44:30] [Server thread/INFO] [STDOUT]: [com.ternsip.structpro.universe.utils.Report:print:70]: [StructPro v4.0][PASTED = SUCCESS][SCHEMATIC = PMC Build Contest map - Life On Mars - master save.schematic][METHOD = BASIC][BIOME = END][LIFT = 0][SIZE = [W=206;H=94;L=206]][POS = [X=-1315;Y=66;Z=298]][ROTATE = [X=0;Y=2;Z=0]][FLIP = [X=true;Y=false;Z=false]][WORLD = Copy of New World][DIMENSION = 0][SPENT TIME = 24.21s]

I do not have any End biomes in dimension 0 - the schematic covered the biomes of Swampland and Marsh. This caused a very bad result in my test world as the schematics for the End are large. The world gen is being done by Lost Cities and Biomes O Plenty - not sure if that makes a difference. Please let me know if you need any more info on this.

Doh, forgot to include versions:
structpro-4.0-1.12.1
forge-1.12.1-14.22.1.2479-installer-win

worldgen:
lostcities-1.12-1.0.0
BiomesOPlenty-1.12-7.0.0.2291-universal

What is the biome name in location this structure spawned? [X=-1315;Y=66;Z=298]

Ahh, yes, by default The End structures allowed to spawn in normal biomes.
You can't change this. Maybe I will make this setup flexible for configuration later. code ref