Contacts missed on the collision detector

Hi, I'm trying to collect every contacts between geoms with specific ID during the simulation.
In every step, I checked all contact list using the following code (mujoco-py).

Code:

data = self.sim.data
for coni in range(data.ncon):
  con = data.contact[coni]
  geoms = (con.geom1, con.geom2)
  # Find contacts between geoms with specific ID
  if (id1 in geoms) and ((id2 in geoms)):
    print('Contact!')

This code usually worked fine, but when I watch the rendered simulation, there are some contacts, which the detector can't catch.
Is it normal for contacts to be missed by mujoco's collision detector? And is there any solution for this?
Thanks!