A very odd issue that I've just started having with the mounted combat system.
Previously, it all worked perfectly. Now, it seems I can only hit (and damage) something if it's in a very specific place in front of the horse. If I swing when the enemy is to the side, they simply get pushed around by the weapon and don't get damaged. As you can imagine, this is infuriating as I tend not to fast travel and mounted combat is great.
No idea what could be causing it though, it's a very new problem.


This is my load order:

Update.esmDawnguard.esmHearthFires.esmNchuzzrezar.esmDeus Mons.esmLevelersTower.esmmoonpath.esmLB_MuchAdoSnowElves.esmClimatesOfTamriel.esmApachiiHair.esmSPIKE.esmRaceCompatibility.esmWARZONES - Civil Unrest.esmUnofficial Skyrim Patch.espUnofficial Dawnguard Patch.espUnofficial Hearthfire Patch.espSkyUI.espDeus Mons_WithNPCs.espAuto Unequip Ammo.espBetter Auriels Bow.espBlackSacramentArmor.espBlackSacramentDBReplacer.espBrawl Bugs CE.espClean  Invisibility Effects plus Eyes Fix - Chameleon Version.espConnys Improved Hearthfire.espCrossbow_Basic_Collection_LListed_EN.espdD - Enhanced Blood Main.espdD-Dawnguard-EBT Patch.espdD-No Spinning Death Animation.espdovahkiinrelax.espAetheriumSwordsnArmor.espexplosivechickens.espFCKagrenacsInstantFortress.espgetoverherebow.espGZD - Ancient Falmer Crown.espHeadtracking.esphorkercompanion.espImmersive Battles.espImmersive Brigands.espImmersive Dawnguard.espImmersive Patrols.espImmersive Travelers.espImmersive Werewolves.espIncreased Bounty & Guild Rewards.espbloodierCombatv1.1.espAncient Falmer Crown Tweak.espLost Art of the Blacksmith.espMadman's Lair.espMagicka Sabers.espMasterTheTimeAndSpaceTOGGLE.espNchuzzrezar.espRagnvaldBookFarengar+Ragnvald.espReally Radiant Raiment.espRun For Your Lives.espsheogorath_shout.espsheogorath_shout_loadscreens.espShootingStars.espskyBirds - Airborne Perching Birds.espSneaky_Serana.espSpace Wiking's Dwemer Exoskeleton.espsqueaky.espSuperSkyrimBros.espTBMTrueSnowElf.espTelekinesisImproved.espTHBoneHawkRingCraftable.espTHCraftableVampireArmory.espThor.espTS_BloodOmNomNom.espUFO - Ultimate Follower Overhaul.espUFO - Dawnguard AddOn.espVampireClothingBugFix.espVampireDoubleWieldBoost.espVampirelordroyal.espVLCollisionFix.espHeartOfThunder.espLustmordVampireArmor.espposesivecorpses.espThe Dance of Death.espYellow_Mountain_Flower.espEMCompViljaSkyrim.espToL_Core_by_Brevi.espRealistic werewolf speed.esparmored-horses.espWRF_by_RolandSir_TAWUTD_DG.espBlaze Of Eventide.espNightingaleBowDmgIncDEFAULT.espNightingaleCrossbow.espJiubQuestMarkers.espKCEAssaultRifles.espBetter Necromancer's Amulet.espP1FlyingRing.espmpn.espmoonpath_questdata.espLB_MuchAdoSnowElves_Quest.espDwarvenMech.espUncle Sheo.espClimatesOfTamriel-VanillaNights-Lvl-2.espClimatesOfTamriel-Dawnguard-Patch.espDwarvenRes.espDragonMasks.espLoreWorthyHagravens.espCastle Stonespire.espPurpleEyes.espBurning Sky.espLimbwoodManor.espCraftable Light Ancient Nord Armor.espWetandCold.espInfernoStorm_Shout.espInsanity's Pale Blade.espRabbitsPlus.espRayeksEnd.espbearmusicianeng.esphrordisdossier.espUlfricForFem.espSkooma Incorporated.espInsanity's Dragonbane.espSmeltingDwarvenMetal.espThe Paarthurnax Dilemma.espGhosu - Project Flintlock.espGhosu - Project Flintlock - Ammo Addon.espDr_Bandolier.esphothtrooper44_ArmorCompilation.espAlternate Hearthfire House Map Marker Optional Version 2.espWerewolfPerksixpanded_1.6.espGuard Dialogue Overhaul.espBoethiaVolunteer.espWhen Vampires Attack.espFantasyEyes.espLostLongSwords.espstormcloakrobes.espTamriel Compendium.espTamriel Compendium - Skill Books.espTalsgarEssential.espEnhancedLightsandFX.espTheAvengersHawkeyeArrowWepMod.espImproved Dragon Shouts.espImproved Dragon Shouts - Dawnguard.espDFG's Blade & Dagger Sheathe Sounds.espWaterArrowsAndBolts.espDeadlySpellImpacts.espPortable Campsite.espDryad Race.espMidasSkyrim.espBFSEffects.espVickysArmor.espSummonSkeletalHorde.espDestructionRebalanced.espDaedric Letters Warpaints.esp

The only horse mod here is the Horse Armors for Skyrim mod, which I've used for a long time without issue. Disabling it has no effect.
I've also tried disabling all mods since I last used mounted combat, with no effect. Re-installing FNIS doesn't do anything either.

Mods that alter animations can have unexpected side effects.
That's one hell of a list you got there.