Which stackable items cannot be placed in the Supply Stash?

Question

What’s the full list of items that cannot be stored in the Supply Stash, despite being stackable?

Examples include gold coins, platinum coins, crystal coins, voodoo lily pollen, chopped lion mane petals, luminescent crystals.

One specific category is stackable items that cannot be stashed because they can only move between your Depot and your Store Inbox. This includes items obtained from the reward shrine, as well as food made by hireling cooks (carrion casserole, carrot pie, chilli con carniphila, consecrated beef, delicatessen salad, overcooked noodles, roasted wyvern wings, svargrond salmon, tropical marinated tiger).

Answer 1

To sum it up: Store items or items that are not tradable on the market cannot be stashed. Here are some examples (I cannot find a fansite with a complete list so I used the examples you had and what I have in my depot currently)

•  Reward shrine items (potions, runes, etc.)
• Hireling cook foods (carrion casserole, carrot pie, chilli con carniphila, consecrated beef, delicatessen salad, overcooked noodles, roasted wyvern wings, svargrond salmon, tropical marinated tiger)
• Tibia Coins (from 25th Anniversary)
• Crystal coin
• Platinum coin
• Spiderweb clouds shreds
• Crystal coin
• Chopped Lion Mane Petal
• Luminescent Crystal
• Wild Desert Rose
• Lightest Missile Rune
• Light Stone Shower Rune
• Milk Tooth
• Veldt Flower
• Snake Maw
• Tagralt Nugget
• Blue Pollen
• Voodoo Lilly Pollen
• Bunch of Winterberries
• Honey palm bark
• Vial of cactus milk

Source:News: Supply Stash

If you'd like to try to find more examples simply go through your depot make sure you stash all the items in the depot and just see which items have quantity.