Thanks for your prompt and detailed response. Per the attached images, these are the settings I currently have in place for Dex to operate (at the current version). With respect to the script, I only installed this during troubleshooting from the advice offered on the site (https://www.pcdj.com/dj-controllers-pioneer-ddj-sx3-is-dex-3-supported/). I can also confirm that the deck has scratching for the jog wheels enabled.
Unfortunately, the troubleshooting advice has not resolved the issues. I use the jog wheels to scratch through the song file and trying to monitor results in the audio routing through the main output and not the headphones.
Any other suggestions?