I've found a bug in the connector, although there may be a reason it is written this way.

From my testing I have found that while i can use IN statement to lookup child items from the parent, for example, contacts on an account, it does not appear possible to do the reverse... query on the contacts then use an IN query to look up the parent on those contacts.

Admittedly we are using customer objects, but it appears that the IN criteria is limited to "references" fields.

I can work around it by adding ID fields to the types of fields applicable with IN statements in the code, but wanted to know if anyone else had found this problem and if it has perhaps been fixed in one of the later versions?