Hello there,

This subject has already been brought here... If you search the forum a bit below, you'll find lots of suggestions.
In short, there's never been any such bugs, but some missions require the player to destroy generators, acquire items in crates, kill specific characters, etc.
Since you haven't yet tackled primary mission 7 - boarding the Chaos ship -, the corresponding secondary missions concern planets Naos (Swamp), Nekkar (Machine World) and Rana (Forest). A quick check in the game files reveals that those random missions are usually "Bug hunts" (kill everyone), "Assault" (same, but on a well defended position) and "Headhunter" (assassinate someone, usually a demon, a sorcerer or a Chaos chaplain). But Rana (Forest) is also flagged as having a potentially completely random objective, in which case you could also have "Search & Destroy" (usually generators) or "Resupply raid" (finding supply crates). So there's quite a few possibilities in your case...
Check which mission you're on and, even if it's only about killing all Chaos forces, use a scanner to make sure someone isn't hiding anywhere.

Oh, and about that mission briefing description, it's normal : the game only tracks the current primary one, regardless of secondary missions and objectives. So you'll never see anything about those when using the "Mission Briefing" button...

Cheers !

Well, I'm a bit embarrassed to say this but you were right. There was one post that had the solution on it. I checked many but I was not thorough enough in my search, so after 1 whole years and at turn 200 I can finally continue my game!

(I will say what I had to do for future stuck players)

What I had to do was to THROW GRENADES at those two yellow generators.

I only shooted at them at first but I NEEDED TO THROW CRACK GRENADE ON THE GOOD SQUARE UNTIL NOTHING WAS LEFT

I kind of blame game design on this since there was 4 generators on the map and only 2 had to be destroyed through grenades. Shooting at them 100 times didn't work but I can't stay mad at the game for that, it's just too good.

Thank you for your help!

No worries ! You don't specifically need to throw grenades at them : close combat is the cheapest method to destroy them. Just make sure you're not using a badly wounded marine for that, since their destruction usually triggers a small light explosion - usually scripted as a Frag Grenade trap.
Every piece of landscape, construction or building that can be destroyed is given an Armor value, pretty much like a vehicle, and Bolters (or light weapons) won't cut through them in most cases. Unless you have a ton of ammo to waste there... So this isn't a bug : just a game design based on WH40k's second edition rules.
But, indeed, due to the way secondary missions, which are based on the random map generator, blend generic backgrounds with (random) specific missions (which add specific scripted parts), they may already contain generators as a part of their background - just random objects -... on top of those specifically linked to a given mission. And this can be a bit confusing, it's true... This is the kind of thing which can be corrected through personal modding efforts.

Good luck for what's next ! It's a very good game ^^...