Dark Matter behaves like a ghost atom. It doesn't interact with matter because it is only waves. It sinks into gravity wells because spacetime can't tell the difference.
A photon being released from an antimatter experiment shows it wasn't large enough or didn't take place in the same conditions at the beginning of time.
Quantum weirdness events (superposition, entanglement, tunneling) do not occur when spacetime is involved. They happen in their own dimension of quantum waves.
Observed particles are in duality mode, the quantum field is still treating it like a wave while spacetime is making it physical.
Dark Matter doesn't have a duality mode, it remains unobservable quantum waves no matter what.