Once I upgraded a weapon (Calamity's Titanium Railgun, to be exact), and my armor (vortex armor, both to level 100), and I noticed that all my items that have buffers (The Amalgamated Brain, for example) didn't have any timer buffer anymore. And holding my railgun froze me in the enemy, and I was invincible the entire time. In fact, I'm permanently invincible. I'll list my mods and the exact equipment on my character for more accurate recreation.

Active mods:
UpgradePlus
Calamity's Vanities
Calamity Mod
Magic Storage
Summoner's Shine
Calamity Mod Music
Better Blending
Unofficial Calamity Whips
Better Chests
HERO'S Mod
Ore Excavator
Statue Drops
Recipe browser
Pylons Prevent Evils
More Accessory Slots (More Accessories)
Boss Checklist
Fargo's Mutant Mod
Teleport to Pylons From Anywhere
Census - Town NPC Checklist
Max Stack Plus Extra
Any Accessory in Social Accessory Slots
Atmospheric Torches
Boss Cursor
Compare Item Stats
Fargo's Best of Both Worlds
Gravitation Don't Flip The Screen
Lights and Shadow
Moon Tweak
No Larva Break
No Sundial Cooldown
Sleeping Passes Time
Stackable Buff Duration
Taller Trees
Alchemist NPC Lite
Which Mod Is This From?
Better Boss Health Bar
Ethereal Boots


Equipment (use the more accessories to copy the accessories)
Unreal Titanium Railgun (Lv. 100)
Vortex Helmet (Lv. 100) (Social: Pretty Pink Ribbon, Living Flame Dye)
Vortex Armor (Lv. 100) (Social: Rain Coat, Black Dye)
Vortex Leggings (Lv. 100) (Social: Cultists Assasin Pants, Siler And Black Dye)
Fishron Wings (Social: Camouflaged Yoraizor's Spell, Fogbound Dye)
Warding Hide of Astrum Deus (Social: Backpack Server)
Warding Magiluminescence (Social: Yoraizor's Scowl)
Warding Flesh Totem
Warding Bundle of Balloons
Quick Bloody Worm Scarf (Social: Astral Bandana)
Menacing Stinger Necklace)
Warding Blood Pact
Warding Heart of Darkness
Lucky Laudanum
Warding Frost Flare
Warding Ethereal Boots (Social: Lucky Old Die)
The Transformer
Warding Sweetheart Necklace
Warding Aero Stone
Quick Amalgamated Brain
Stress Pills
Menacing Ranged Level Meter
Hallowed Rune (Social: Rainbow Cursor)
Empty
Warding Master Ninja Gear
Warding Grand Gelatin (Social: Warding Archaic Powder)
Regenator (Social: Hard Ocean Crest)
Warding Deific Amulet (Social: Lucky Ancient Chisel)
Angel Treads
Warding Nuclear Rod
Warding Solar Insignia

Originally posted by Myraseth:

Once I upgraded a weapon (Calamity's Titanium Railgun, to be exact), and my armor (vortex armor, both to level 100), and I noticed that all my items that have buffers (The Amalgamated Brain, for example) didn't have any timer buffer anymore. And holding my railgun froze me in the enemy, and I was invincible the entire time. In fact, I'm permanently invincible. I'll list my mods and the exact equipment on my character for more accurate recreation.

-..

Hey, thanks for reporting it! Of the listed accessories and of the gameplay changing mods I think I narrowed down your apparent immobile immortality to having an Amalgamated Brain (and possibly Transformer) equipped and getting hit.

AB's brain of confusion and TT's sparks forget the GlobalItems they come from and my mod expects every item to never lose it's GlobalItem. When the projectile goes to reach the GlobalItem it fails and that cascades into different bugs including somehow being immortal.

I only found an issue with A.Brain but it's possible it was causing other issues for you, patch is out now so steam will prompt an update or if it doesn't just unsub and resub.