I'm new to these forums, so forgive me if the "fix" isn't in the right spot. Avid and Long time user of NullDC, made the switch recently to Demul when setting up my LaunchBox collection, and came
across an issue with the DS4 Pad on Demul, the D-Pad refused to map and kept auto-mapping to "Joy1_anl3" and scattered through tons of forums, and came out with nothing.
While looking through DS4Windows, I noticed the "Tilt" was constantly moving a little bit, and clicked the setting "Hide DS4" and that has resolved any issues with mapping the D-Pad, for whatever reason
it kept using the Gyro on the DS4 to map the D-Pad as "Joy1_anl3"

If you have been having issues with a DS4 pad similar to my issue, I hope this helps.