Not Sure Is This Bugs Or WAI? Because I Typing Jigsaw Blocks
"Target Pool:" minecraft:woodland_mansion
" Name:" minecraft:building_entrance
"Target Name:" minecraft:building_entrance
"Turns into:" minecraft:structure_void
And I Click Generate (button) It Does Not Work And I Tryed Multiplie Times But It Not Work, But Villages Works
Sorry But I Don't Have Screenshot But You Can Reproduce Here As You Why Not Work.
Woodland Mansions don't use jigsaw blocks. Currently only villages use them.