When you make a connection from Qlik to a database, you create a "real" connection. Oracle creates logical connections to the database whenever you start a transaction (or a transaction-like event). The Oracle name for these logical connections is sessions. Each user is allocated a limited number of sessions. If you run out of sessions, Oracle can act like it is no longer responsive.
If you have lots of calls to Oracle in a load script, you can run out of sessions. To test this, go into the data load editor and move the problem call to the top of the load script, just after the Qlik connection to Oracle. If it runs quickly when you call it first, then there is a good chance that Oracle has run out of sessions when it is called later in the script.
I am not sure how the connection from Qlik to Oracle manages sessions. I know that some other BI tools do not release Oracle sessions until the end of the load script. If you are running out of sessions, you either need to redesign your data load so that you make fewer calls to Oracle, or you need to find somebody with privileges to add more sessions to the user. This would not be a Qlik issue. This would be an Oracle issue.
Another way to test this would be to run the existing script to the point that it hangs, and then connect to Oracle with Query Builder or some other tool and try to execute statements. If the same user can't execute statements in Oracle when the Qlik load script hangs, then Oracle has hit some capacity limit for that user, such as sessions.
