More than likely this is a side effect of Oracle-specific functionality in the Oracle JDBC driver that SQL Developer uses (because it is from Oracle and works with Oracle) and Ignition does not (because it only use the cross-brand standard features of JDBC). Ignition also does no streaming of result sets--it accumulates an entire result in its own Dataset format, then hands it off.
Consider writing a simple java program that exercises the same query using JDBC and without using cursors or any brand-specific features.