Addition to stock is not working in EWM

Hi everyone,

In my warehouse, a bin can contain 6 handling units of one product with different batches.

I have set up a storage type with addition to stock/empty bin strategy as below:

Storage Behavior: General Storage

Putway Rules: 2

Mixed Storage: 2

Mixed Storage in HU: 1

However, when I create the WT, the system only determines the empty bins for my putaway WT.

Could anyone shows me what is wrong with the configuration?