When you have a chest/factory with only default capacity, and you try to move a stack from your inventory to that chest/factory. It will give you a "inventory too small" warning and not do that even though there's enough space. Most likely it doesn't see the default chest size as real capacity?

How to reproduce:

1. put some low quantity stacks in your inventory
2. open up a new chest with no linked cargo blocks
3. shift click a stack, make sure its volume isn't higher than the default capacity of that chest
4. stack won't move and it will give you a "inventory too small" message