Contributions aren't listed if the most recent edit (not the only edit) made by the user is a minor edit.

It would be great if this bug could be solved by having a configurable Contributions page, choosing to list minor edits, pages created, and/or pages edited. But that's a feature request, not bugfix.

So why does

SELECT old_title FROM old WHERE old_user_text="$theuser" AND old_minor_edit<>\ 1

exclude *all* entries which have a minor edit?

Maybe it needs to be

SELECT DISTINCT old_title FROM old WHERE ....

or perhaps

SELECT old_title FROM old WHERE old_user_text="$theuser" GROUP BY old_title HAVING old_minor_edit<>1