Breaking it down into the constituent parts:
It comes together to form "not having a gripping point somewhere (but I do not know where in particular)".
The "gripping point" represents a step towards understanding for which if you manage to "grab" it, you can start to understand more of the intangible phenomenon of intuition.
Opinion: Think of it as rock-climbing, and every hand-grip (clue to understanding) you manage to grab, hold on and pull yourself up brings you closer to the top (complete understanding)
To continue the metaphor, imagine rock climbing while being blindfolded. You recognize that there are hand-grip points around you, but you reach out and cannot find any, so you do not have a gripping point. But you know it is somewhere, just not exactly where. It is also possible that there are no hand-grip points around you, because you were blindfolded from the start and led to the wall, you might not even know that it could be an unclimbable smooth wall!
Bringing it back to trying to understand the phenomenon of intuition scientifically, the "blindfold" symbolises scientists trying to look into an unknown field. But scientists assert that there must be some systematic way of understanding it so they look for the "hand-grip points" in an attempt to understand and "ascend the wall". However because little is known about the nature of the wall, it could in fact be a flat smooth wall with no way to climb over.
どことなくつかみどころがなく
from seeing it in the exact same sentence in the exact same book! Extra +1s for synchronicity if I could!生体{せいたい}
where it should be正体{しょうてい}
.