So I've just reinstalled Oblivion with FCOM and a few other mods and I came across a bandit with an invisible chest so i figured I must be missing a texture or something. I found out the armour was called "Composite Cuirass" but I don't have a clue which mod this is from as I have quite a few. I'm not sure if it could be from OOO, Frans, WC or anything. Can anyone help?

Post your Load Order, I had this problem because of a bad Install Order, but you may not have a clothing and armor replacer for the body replacer(s) you are using.

Fran's has Composite Cuirass, did you install the resources correctly? Maybe refer to the http://www.gamesas.com/index.php?/topic/1172894-relz-fcom-convergence-and-ufcom/ and check whether you installed anything wrong,

Oblivion.esm
Francesco's Leveled Creatures-Items Mod.esm
Francesco's Optional New Items Add-On.esm
Oscuro's_Oblivion_Overhaul.esm
Mart's Monster Mod.esm
FCOM_Convergence.esm
Better Cities Resources.esm
HorseCombatMaster.esm
Unofficial Oblivion Patch.esp
DLCShiveringIsles.esp
Better Cities .esp
Francesco's Optional Chance of Stronger Bosses.esp
Francesco's Optional Chance of Stronger Enemies.esp
Francesco's Optional Chance of More Enemies.esp
Francesco's Optional Leveled Guards.esp
FCOM_Francescos.esp
FCOM_FrancescosItemsAddOn.esp
FCOM_FrancescosNamedBosses.esp
Fran_Lv30Item_Maltz.esp
Symphony of Violence.esp
WindowLightingSystem.esp
Book Jackets Oblivion.esp
Living Economy.esp
ExnemRuneskulls.esp
FCOM_ExnemRuneskulls.esp
Bob's Armory Oblivion.esp
FCOM_BobsArmory.esp
Loth's Blunt Weapons for Npcs.esp
FCOM_LothsBluntWeapons.esp
Oblivion WarCry EV.esp
FCOM_WarCry.esp
Oscuro's_Oblivion_Overhaul.esp
OOO-Water_Weeds.esp
OOO-Container_Trap_Instant_Effects.esp
Mart's Monster Mod - Additional Enemy NPC Vars.esp
FCOM_Convergence.esp
FCOM_RealSwords.esp
FCOM_SpawnRatesSlightlyReduced.esp
Mart's Monster Mod - More Wilderness Life.esp
FCOM_SaferRoads.esp
FCOM_NoReaversInGates.esp
Mart's Monster Mod - Extra Wounding.esp
Mart's Monster Mod - Looting NPCs & Creatures.esp
Mart's Monster Mod - No Beholdens.esp
Mart's Monster Mod - No Balrogs.esp
Mart's Monster Mod - Less Bone Loot.esp
Mart's Monster Mod - Safer Quest Locations.esp
Mart's Monster Mod - Dungeons of MMM.esp
Mart's Monster Mod - Hunting & Crafting.esp
Mart's Monster Mod - Farm Animals.esp
FCOM_DiverseGuardUnity.esp
FCOM_BobsGuardUnity.esp
FCOM_HungersUnitySI.esp
OOO-WaterFish.esp
KnightlyArmory.esp
Mighty Umbra.esp
FCOM_MightyUmbra.esp
Castle_Seaview.esp
JQ-Fighters_Guild_United.esp
FCOM_FighterGUnited.esp
Harvest [Flora].esp
Harvest [Flora] - Shivering Isles.esp
Short Grass V3.esp
Alternative Start by Robert Evrae.esp
RealisticForceMedium.esp
RealisticMagicForceLow.esp
Dark Dungeons - SI.esp
bgBalancingEVCore.esp
Mart's Monster Mod - Resized Races.esp
bgBalancingOptionalLessHealth.esp
bgBalancingEVOptionalClasses.esp
bgBalancingEVOptionalFangs.esp
bgBalancingEVOptionalMoreEyes.esp
bgBalancingEVOptionalFCOMAdditions.esp
Better Cities Full.esp
Better Cities - VWD of the IC.esp
Better Imperial City.esp
Better Cities Full FPS Patch.esp
Better Cities - Knightly Armory.esp
Better Imperial City FPS Patch.esp
DBAssassin.esp
Francesco's 7 days respawn time - 1-16 day lenght rescale.esp
FCOM_Archery.esp
Bashed Patch, 0.esp
DeadlyReflex 5 - Combat Moves.esp

I don't use any body replacers though I did have Deadly Reflex 6 which comes with an absurdly stupid naked texture replacement which was "accidentally" put in but I disabled the DR 6 omod and it's back to normal.

Yes I did install the resources package, it's called "FraNewItems" In my bsa folder.

I did recently delete my ini file because my main menu buttons were going invisible, could that have anything to do with this?

Try renaming it to FCOM_Convergence_FraNewItems.bsa.

Fixed it perfectly

Thanks alot!