Hi
@zooooot
As I said in Discord this is not enough information to go on with.
There are many reasons this could happen, Item Filters, Item Restrictions, bad setup, etc...
Please give us more information:
Are you using the UCC with UIS? Did you download the integration? Did you follow the documentation to convert a UCC character to UCC/UIS bridge?
What type of item isn't showing, is it mutable/immutable, unique/common, are you using special ItemCategories?
Does the Item disappear from the Item Collection at runtime?
Do you have restrictions on your inventory?
What type of Inventory UI are you using?
What version of are you using (make sure to check in our Editor, not the package manager)?
etc...
Also send us screenshots, or even make a video and share it here using
https://streamable.com/
If you are getting any errors or warnings make sure to send us the full error/warning stack.