how does Hunter/Vigilante "Detect Concealment" work on most?

[Axelmania]

Mystic China pg 54 on the Hu Ching (Fox Spirit)
"can travel virtually invisibly (to humans, anyway) and soundlessly"
"Professional hunters (like the Heroes Unlimited special training character; the Hunter/Vigilante) will have a "feeling" if they are observed by a fox form for more than a minute or two, and can roll on
their detect concealment skill every five minutes in an attempt to locate/identify the Fox Spirit."

This ruling apparently could apply to more than just the Hunter/Vigilante. It doesn't exactly define what a "professional hunter" requires, but based on what the class had in HU1E (2nd wasn't yet out in 1995 when MC was published AFAIK) we might assume it's anyone who has the Tracking skill? That's one of four mandatory skills all H/V had in 1e, and the others (Wilderness Survival / Land Navigation / Hunting) don't seem as directly related to hunting in the sense of having instincts of being observed (ie why would wilderness survival or land navigation help you know a Fox Spirit was watching you in a city setting?

Ironically the "Detect Concealment" skill which Mystic China calls out actually wasn't mandatory: it was an optional selection where you could select seven from a list of sixteen.

Though I think in practice it's more like "seven of eleven" since only seven got % bonuses and it'd make sense to go for those and if you wanted the other ones lacking a bonus, just get them as one of your 8 secondary skills. So a high % of them would've picked Detect Concealment.

Should professional hunters (like hunter/vigilante) get a "feeling" if ANYONE is observing them for 60+ seconds, or should that be a weird drawback of fox form giving some kind of supernatural warning out to hunters?

Furthermore: should this use of Detect Concealment (rolling once per five minutes) be useful in finding other people who are hiding and invisible? Like for example could you use Detect Concealment to find even an invisible superhero or mage?

There's no mention of this under the human form of the Hu Ching, nor in the Pure Positive Chi form, so I'm guessing it might be some weirdness about being a fox.