Wow that must be a different GUI completely then. I don't have that camera, but have several other Dahua PTZ models and auto tracking is based on a preset and being set up within each preset.
Since you won't post videos or screenshots, it is all a stab in the dark, but keep in mind when the PTZ moves based on a spotter cam, it can take a few seconds before the "algorithm" is set up to start tracking, so depending on how close you set that up spotter trigger to the field of view of the PTZ, it may miss it because the object is out of the IVS rules by the time the camera settles into the preset.
Just because it isn't tracking doesn't mean is becomes disabled or paralyzed - you may have the field of view of the PTZ too close to where the spotter field of view is and it simply misses tracking due to the delay as the PTZ pulls up the tracking parameters.
The only way to know for sure is to open up the PTZ camera GUI and watch the slider - does it actually turn off when the spotter cam is triggered? I can mimic that by calling an API for the PTZ when the spotter cam is triggered to turn off an IVS rule and I can watch it turn off when triggered.
Here is great thread and example showing how the spotter cam calls the PTZ to a spot ahead of the motion so that it has time to swing to that preset and set the tracking parameters and then start tracking.
With more people looking to get a PTZ and asking about it moving to a preset and auto-tracking I decided to put a video together. This shows how the PTZ goes from parked to a preset based on an IVS trigger from a spotter camera. From this preset the PTZ has its own IVS rules to tell it to...
ipcamtalk.com