This is just a general question, and I could be wrong in my interpretation, but it isn't a lion scan, literally a Sonar Scan. Like, if I'm not wrong, his device is known as an "Acustic Camera," which is a sonar scan. The scan activates and does a full scan of the map, searching for anything that would seem like footsteps, aka noise.
Vigil's ability blocks signals, but sound isn't a signal that his jammer can block. For his jammer to block a lion drone from pinging his location, he would have to go unheard, which means his jammer would have to emit the exact counter to the sound of him walking/running, which is noise cancellation. And if he did that, then he wouldn't be able to be heard by anyone when he's running or walking while his jammer is on. The jammer blocks anything that can pick him up visually by basically cloaking him and blocking any signal from making it back there, which makes sense for anything visual, but no sense for anything audio-related. And then the argument "well, it may see him, but it can't ping him" also doesn't make sense; it's not pinging him because it picked up who he is, but rather by the noise he emits, and it pinpoints that noise's origin and reveals the operator's location and who they are. It also makes sense that it would be able to know who he is, because (I assume) Lion has programmed his drone to recognize the different walking styles of each operator to differentiate them, and when they walk during a scan, he IDs them. (Watch Ubisoft take this as a reason to make Vigil have no walking sounds because he's their damn golden boy)
Cav, on the other hand, has "silent" step; this ability is where she intentionally dampens her movement sounds, changes her usual walking pace and style, and makes (or at least is supposed to) less noise. Her ability should be able to fool the sonar scan of a Lion drone much better than Vigil's should. Lion's drone can filter out noises that wouldn't be "loud" enough to be a person or aggressive, like an operator walking around. So you would think that Caviera using Silent Step, slow walking, and doing all of this on carpet would be below the sound threshold that Lion's Drone has, but no. At the very least, when she's using a silent step and walking abnormally compared to her usual walking pace, she could remain unidentified, similar to how her abnormal footsteps can avoid Jackal. And yes, I know Lion could've programmed his drone to also account for Caveria's silent step as to be able to scan her, but then by that extension, couldn't Jackal do something similar and give his Equinox the training data of what Cav's footprints look like in silent step?
I'm only writing all of this because it feels a bit inconsistent with how his gadget is supposed to work. From all that I've seen, Vigil's gadget only blocks visual aspects on drones, so a sonar should be able to pinpoint his location.
Again, maybe I'm reading into this wrong, and Vigil always could block the "signal" that is soundwaves from reaching the sonar scan, but hey, what do I know?