I just beat Halo CE Halo 2 Halo 3 Halo 4 all on legendary and I don’t have the helio skril. I did use cheats on halo CE and halo 2 (Bandana skull) but I didn’t get the achievement for Halo 3 which I didn’t use any skulls on but, I got it on halo 4. Both the halo 3 legendary achievement and Legend achievement (beat all halos 1-4 on legendaary) are stuck at 55% completion and I’m really confused how that happened. Is this happened to anyone or does someone know why.
I’m not sure if this was purposeful or accidental, but please don’t post the same topic multiple times! 
The unlocked topic is available here: https://www.halowaypoint.com/en-us/forums/e0d9938206f04a598ce84f2c8cadce02/topics/helio-skril/4281236c-eca2-42bd-a410-80a3f955ebbf/posts