Incomplete query answering for rules with partially grounded atoms in the body

[alloka]

Using Rulewerk Syntax, consider the following example:

We have the following edb facts:
cont(d12).
cont(d6).
cont(d13).
cont(d7).
cont(d3).
cont(d2).
fetch(d11,b11).
fetch(d3,b5).
fetch(d1,b2).
fetch(d11,b12).
fetch(d3,b6).
fetch(d3,b4).
fetch(d1,b1).
fetch(d3,b3).
fetch(d8,b7).
offset(d12).
offset(d15).
offset(d6).
offset(d8).
offset(d2).
putOn(b11,d13).
putOn(b1,d3).
putOn(b5,d8).
putOn(b4,d7).
putOn(b3,d6).
putOn(b11,d12).
putOn(b1,d2).
putOn(b1,d4).
putOn(b11,d14).
putOn(b6,d9).

and the following rules:
buildWall_p(?x1, ?x0,!p) :- inv(?x1, ?x0), offset(?x0).
inv(?x2, ?x1) :- inv(?x2, ?x0), buildWall_p(?x0, ?x1,?p).
inv(?x2, ?x1) :- fetch(?x2, ?x0), putOn(?x0, ?x1), cont(?x1).
iterate(?p) :- buildWall_p(d1,d2,?p).

where any variable with a ? before is a universal variable and the variable with a ! before is an existential variable, d1 and d2 are constants.

Querying buildWall_p we get the following answers:
?x0 -> d11, ?x1 -> d12, ?p -> _:null1_3_0
?x0 -> d3, ?x1 -> d6, ?p -> _:null1_3_1
?x0 -> d1, ?x1 -> d2, ?p -> _:null1_3_2
?x0 -> d1, ?x1 -> d6, ?p -> _:null1_3_3

which means that we have an idb buildWall_p(d1,d2,_:null1_3_2), and that means that the rule with iterate(?p) in the head should fire, but that is not the case as if we query iterate(?p) we don't get an answer.