Are you testing in the Handheld AR project or your own project?
I’d suggest testing initially in the Handheld AR project if you are not doing that.
One thing that we noticed is 5.3 & 5.4 seems to sometimes have AR linetrace issues. So if you are tapping the screen to place your AR object, sometimes the line trace will return the wrong location and your object will not get placed on the ground. This can look like a tracking issue as the object will appear to not “stick to the ground”
One way to see if this is what is happening is to put your device upright on the ground pointed at your CG object. from that angle, you should be able to tell if your CG object is properly on-the-ground.
might be worth testing.
-e