Queries containing a UNION with an ORDER BY are producing unexpected results in CTC Query Testing

I am getting unexpected results (all sources) on 17 queries containing a UNION and ORDER BY. The ORDER BY isn't working when there is a UNION involved. These queries were producing expected results prior to the holidays. Below is a sample query:

RDBMS_Test_Queries_6500_TestQuery32" value="SELECT StringKey FROM BQT1.SmallA WHERE IntKey >= 0 AND IntKey < 15 UNION SELECT StringKey FROM BQT1.SmallB WHERE IntKey >= 10 AND IntKey < 30 ORDER BY StringKey DESC

The interesting thing is the queries do work with a UNION ALL.