Ahh, I got the very same problem.
The weird thing is that it comes from the picture plan, I have no idea what does the App does so weird that many antennas and trees are just erased.
I started in Pix4D, before going manual I also used the App Planner and it wouldn't erase trees or antennas.
I've no idea why would DD do this, have you an answer already?
I used the photos taken in DD on the Pix4D Program to test that.