PRC: Update Project and Resource Base Summaries is locking itself

Hello,

We are running Projects 12.1.3, delta 6.  It has run well for almost a year.  The PRC: Update Project and Resource Base Summaries concurrent request creates three PRC: Process Project Financial Data threads.  Twice in the last week, the threads have locked themselves, and we had to terminate the next morning.  We cannot create this for an SR, so I would like to know if anyone else has experienced the threads locking themselves, and is there a patch for this already?

Thank you, Kevin