Oh, and as a second suggestion: Consider having them roll, but the roll is to determine if they get Deja Vu, or the World gets Deja Vu, or Morale or whatnot, and the Clue happens either way. This can be usefully be framed as 'do you easily find and digest this detail, or does it take you a moment or remind you of something you don't want to remember, in an inchoate way.'
It's a good way to split the difference between knowing they really need the Clue and wanting it to be something they can engage with.
That’s good framing - you get the result but with a little flavoring, and maybe some resource gain / loss. I’ll try that next time.
How about when there are many clues in a place, some a little bit more hidden? For example, I had a ring hidden in some high grass that the players never rifled through, and I didn’t know if how heavy handed I should have been in pointing it out.
My advice on that front is just to have more clues than you need, and so if they miss a few juicy ones it's not the end of the world. You can tell them after they solve the Case! There's a Reconstructure expertise, if I remember my own writing correctly, that also lets them know if they haven't found any clues you had pre-written.
If they absolutely need a clue, force it (offer them a roll where no matter what, they find the clue, but a bad roll stings a bit) as discussed above. Missed clues are actually good, because they mean the players genuinely get to carve out their own path through the mystery - as long as there's enough clues to get there in the end. You may have to generate some on the fly to make sure, but again that helps the players take ownership of their solution.