MechWarrior 5: Mercenaries

MechWarrior 5: Mercenaries

YetAnotherClanMech
Why can't the modules be removed in some mechs?
I noticed that in some mechs you can't remove modules such as:
- engine core
- xl engine
- double heat
- structure
- armor

This occurs in various mechs, such as all Timber Wolves.
I mainly write with these modules FIXED, I don't know why this is the case, I don't have any mods that mess with it.