Game version: 7597 to 7602 (latest)
Operating system: Windows 10
Tiles or curses: Tiles (retrodays. NOT retroascii)
Mods active:
DDA
Filthy clothing
simplified nutrition
generic guns
makeshift items
more survival tools
alternative map key
mining
npc traits
boats
vahicle aditions
tanks
disable mutagens
no sci-fi
stats through skills
Items on floor are recognizable by their tiles until v. 7596
Items on ground are shown as white squares instead

Generate a world using any version up to 7596, Update to latest version. Do anything with that world, be it either reset the world and use a preset to make a new character, or load a previous save. Items on the ground will be glitched.
Which of retrodays tilesets are you using?
When I go to the graphics options, it just says "retrodays". It's not retroascii, if that's what you are asking.
I'm sorry I can't help you resolve the bug I'm reporting myself. I'm not knowledgeable enough.
Can confirm. Item sprite is not shown when there are multiple items on the same floor tile (blue border). Weather animations sprites are also borked.
Don't worry. I know what's wrong and fix it soon.
Thank you! That was fast.