Query node not working in Export Definition

So I have a custom query node that we built a year or so ago, and it is working very nicely.

We recently tried to add some fields from it into an export definition. The ED saved just fine and can still be edited, but now when we try to use it in an export process, the process generates that dreaeded error “Object Reference is not an instance of an object”.

If I take those fields out of the ED, it runs fine again.

AGAIN, it works fine in query.

Here's the sepc:

spec.xml