When a LOOKUP is done on a parent item in a module, the result does not resolve to the column with that respective parent. Subsequently the value shows 0.
To reproduce:
1. Create list with leaf item and parent
2. Create module with column 1 as "Data", column 2 as "Parent", and column 3 as "Lookup", using list from 1. as the dimension.
3. In column 2, set formula to "PARENT(ITEM(List))"
4. In column 3, set formula to Data[LOOKUP:Parent]
Column 3 displays 0