Recent double-slit experiments with massive molecules, such as fluoro-fullerene consisting of 108 atoms and atomic mass 1632, see heavy matterwave experiment, show that the interference fringe will disappear if the FF molecule emits a thermal photon, or collides with a gas particle, where the mass of the gas particle is immaterial. I am having a hard time understanding some of the explanations given for this phenomena in different places, which I think are as follows: 1- The emission or collision produces an entangled pair. Therefore, as shown in entanglement experiments (Scully, Walborn), the fringe gets obscured by the other entangled member, and can only be revealed if we capture the entangled particle, and do a coincidence selection. Original fringe cannot be revived. 2- Upon emission or collision, the wavefunction collapses and the molecule gets localized, and the partial wavefunction due to the other slit disappears, and so does the fringe. No need to explain this in terms of entanglement. Fringe cannot be revived. 3- The emission or collision passes which-path information to the emitted or collided particle. Although this information has not been measured, in principle it can be obtained. Thus the Principle of Complementarity dictates that the fringe would disappear as the which-path becomes known. Furthermore, if we erase this information, the fringe can be revived. These are different and contradictory explanations. Any and all insights into this phenomena is highly appreciated. Thanks.