The issue with all these reports is that there is a distinct lack of detail surrounding the sighting. At most its visual reports and very blurry IR footage. Zero mention of anything else.
Lets take an example of the Tic Tac from the incident, that was supposedly moving very fast.
If it had a physical presence, ie could interact with the world, it would seem very likely that pilots would describe the resultant shockwave. Depending on the possibilities of the propulsion system, its highly likely that you would get EM interference, possibly even some physical disturbance if the craft came close to the observing plane.
If it didn't have a physical presence, like it was folding space or something and traveling in a bubble, then it seems very, very strange that an advanced civilization can fold space to effectively travel without any impact on the world, but let the EM radiation that is light/heat leak out. You would think they could just be fully invisible.