Halo 2 Anniversary skulls dont appear on legendary

Hi all!

Sorry if this has been discussed somewhere before.
I can’t find any related info anywhere.
My problem is: I play Halo 2 Anniversary in MCC.
I am going for the skull collection achievements.
I play the levels on legendary as I should.
The skulls simply don’t appear where they have to be.
The only one I could pick up is Blind on Outskirts, that doesn’t require legendary.

Is there any solution for this?
Has anyone else had this problem?

Which ones are you trying to get? Some may or may not appear based on some active settings.

Thank you for the answer!
I tried wrong it seems. I watched some videos on locations. So I tried the one on the armory first, and I did’nt know that I have to wait before getting in the lift. Then I tried the IWHBYD on outskirts. I followed the guide, but i guess it’s some glitch or bug that it’s not always there. So in the end all is fixed and I am able to pick them up, it was just me trying the wrong way and not knowing.