I found an article which more closely demonstrates what I am trying to do (use INOUT parameters with a stored procedure):
https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z0000019LN8SAM&l=en-US By itself, this did not fix the problem.
EVENTUALLY, I got it working by combining advice from another article:
https://forums.ni.com/t5/LabVIEW/2013-Database-Toolkit-Create-Parameterized-Query-Postgres-Bug/m-p/2...
In summary, I had to modify the Create Parameterized Query VI (so that it handled the Use Stored Procedure? input like it used to prior to LV2012 or LV2011 [not sure when the change was made that caused the problem]) AND by following the caveat about reserving a memory buffer for the “value” portion of the Parameter cluster for OUTPUT or INOUT parameters.
This is a very obtuse problem and perhaps it is only pertinent when using MySQL databases. I would say there are two bugs at play, one of which is known but unresolved for many years (the second article I mentioned) and the other which could be resolved by at least documenting the memory buffer requirement in the help pages (first article).
