Multiverse, check out the Martin VBAT.
The V-BAT drone is a very slow example of a tail-sitter, which is a type of VTOL that requires tilting the entire aircraft. With a tail-sitter, the transition between vertical and horizontal flight is far too slow and obvious to explain many of these unidentified vehicles. It's far more likely that thrust-vectoring nozzles are used, similar to those found on the Harrier or F-35B.
BAE Systems MAGMA UAV is an experimental drone used to demonstrate maneuvering in the air without the use of any flight control surfaces. The flaps that it has are not technically required and are only used as a fail-safe.
The following is speculation, and I don't claim to have sufficient evidence to support this. These unidentified vehicles seem to be designed for the most covert activities, with evasion and deception being integral aspects of their design. I seriously doubt that these "vehicles" are capable of violating any physical laws. What is far more likely is that these "vehicles" are designed to make it appear that way. This could allow them to evade not just detection, but comprehension as well.
These "vehicles" may need something like a turboramjet to allow for both supersonic speeds as well as speeds low enough for hovering or vertical take-off and landing. Reaching hypersonic speeds would require an additional engine, such as a scramjet or even a rocket engine. Instead of obvious flight control surfaces, thrust-vectoring nozzles could be used to account for all aspects of stability and velocity. There might even need to be a second engine on the front end, reserved for deceleration. Alternatively, both ends could be virtually identical, and it might not make much of a difference whether the "vehicle" flies forwards or backwards. A rocket engine could be ignited just for the duration of a turboramjet spooling up or down, eliminating much of the actual acceleration time. However, if the rocket fuel capacity wouldn't be realistic for longer flights, a cold gas thruster could be used instead, with a tank of compressed air that is refilled by one of the jet engines during flight. This wouldn't allow for spaceflight, but it could provide the kind of burst needed for extremely fast acceleration, or even short pulses for stability, which could function like the thrusters used by the Multiple Kill Vehicle. All of the unpowered engines would add a whole lot of extra weight, but if thrust-vectoring could eliminate the need for any wings or stabilizers, then that might be less of a problem. This set of features would likely be far too dangerous for human pilots, suggesting that this would be a form of drone.
If some of these unidentified vehicles are drones in the form of double-ended lifting bodies with VTOL and hovering capabilities that also require no wings, stabilizers, or flaps, then the Tic Tac and lenticular shapes start to make sense, being equally aerodynamic both forwards and backwards.
I mean, we have lots of evidence pointing to that being the case. That's why people have been searching for candidates of a theory of quantum gravity for decades. That said, the predictions of general relativity are so incredibly accurate that any theory of QG is going to have the same relationship is GR that GR has to Newtonian gravity: in a suitable limit, QG will reduce to GR.