I’m still saying it isn’t a reactionless drive. The laws of physics apply to this device and it’s results can be explained via other hypotheses that do not violate the laws of physics.
Photons can transition to a particle-antiparticle pair for a brief moment of time. Virtual particle production is difficult to directly observe—the evidence for their existence as more than a mathematical device, is based on observations of random perturbations of the hydrogen atom’s electron.
As a pair of charged particles, an interaction with electrical / magnetic fields is allowed, and transfer of momentum can occur. The lifetime of the virtual particle-antiparticle pair is very short, so interaction with the surrounding environment is limited.
A cavity filled with electromagnetic fields will have a fleeting opportunity to transfer momentum to any particles briefly present; and, thus the low thrust from the device at present. Engineering may be able to improve results with a complete understanding of how the effect occurs.
https://www.scientificamerican.com/article/are-virtual-particles-rea/